What were the songs that made you realise you wanted to be a musician?

When I first started out, I sang a lot in church. Amazing Grace was the first song that I can remember ever singing. Gospel was probably the main kind of music I was into. Then I got into Bob Wills (1) and Hank Williams and Frank Sinatra and Louis Armstrong, all those great singers. Ray Charles came along – I loved him. Ray Price. The greatest singer there is, I think, is Ray Price (2).

Sinatra was a big hero of yours, of course.

Yes, he was. Still is. He is my favourite singer. And I read somewhere that I was his favourite singer, so that really made me happy.

There's no better compliment than that …

That was the big one.

What did you love about his singing so much?

I loved his voice, I loved his phrasing, I loved his acting, I loved his attitude. Everything about Sinatra was good. He had the ability to pick great songs and once Sinatra had sung them, that pretty much was it. He pretty much put his stamp on everything.

The early 50s seemed like a golden age, with people building popular music brick by brick, didn't it?

For me it was. It's where my music came from. I used to work in the cotton fields a lot when I was young. There were a lot of African Americans working out there. A lot of Mexicans – the blacks and the whites and the Mexicans, all out there singing, and it was like an opera in the cotton fields and I can still hear it in the music that I write and play today.

When you started out as a songwriter, how far did your ambitions extend? Did you always want to become a singer as well?

Honestly, when I was growing up I had no idea that I would succeed to this extent. I would have been very happy – I was a big Gene Autry and Roy Rogers fan, and I liked to ride my horse and throw my rope and shoot my gun and I loved all that kind of music – to be another singing cowboy. The fact that I got to do songs like Stardust and sing with Ray Charles and do a lot of things with other singers – Frank Sinatra and I did a couple of things together – that was beyond anything I could have dreamed of.

Is it hard to stay interested in songs you wrote 60 years ago, but which you know your audience still wants to hear?

I really enjoy singing those songs, and I have yet to get tired of them. When I do get tired of one I replace it with another one, cos there's a jillion songs out there I can do. The band has no idea what I'm going to do next, cos I have no idea. I just play it off the top of my head.

You don't feel the urge to do a Bob Dylan and keep your best-loved songs fresh by making them unrecognisable?

That probably works for him, and I'm sure my take on them each night is a little bit different. But basically I do 'em the traditional way. I enjoy being out here and I enjoy playing the music, and as long as the people show up I hope to be out here – we haven't slowed down any, we do 150 shows a year. I try to split it up so I can spend time around the house with the family, the horses and the things I love doing when I'm off. It seems to be working pretty good. I work a few days and I'm off a few days.

Was Nashville's audience as conservative as the Nashville industry when you headed off to Texas to play "outlaw" country in the 70s?

When I left Nashville I went to Texas because that's where I came from, and because I was playing in Texas a lot in different places. And I saw hippies and rednecks drinking beer together and smoking dope together and having a good time together and I knew it was possible to get all groups of people together – long hair, short hair, no hair – and music would bring them together. I called Waylon Jennings and I said: "Waylon, you need to get down to Austin because it's really happening here. There are people here with hair dragging the ground that will love your music." He laughed a little bit, then he came down and found out I was telling the truth.

Did the breakthrough you made with Red Headed Stranger in 1975 surprise you?

I didn't really realise how large it was gonna get. I had nothing to compare it to. As it was happening, it was a slow thing, so I sort of went along with it. I was just feeling grateful that the night before I woulda had a bunch of hippies and rednecks in together having a good time. I didn't know how big it could get. Today, as I look back on it, I mighta been a little bit shocked about how big it was gonna go.

You've never been afraid to take risks – is that what separates an artist from a pop singer?

I don't know. But I do know that if you're with a record company and you're with them for four to eight years and you're under their control, and their producers produce you the way they think you should sound, that may be OK for some people, but for me it was not a good idea. In Nashville, the songs that I was singing and playing and the styles they were in were not the direction I needed to go. But in Texas there was a lot of people who liked the kind of music I was playing. They liked the country – the real solid hardcore steel guitars and fiddles – they still do. They like the real country music – not that there's anything wrong if you put strings and horns on, but for me it waters it down. Personally, I want to hear country music with a steel guitar and a fiddle; I want to hear Stardust with strings. That's just me.

You have been politically active on the left for a long time, but as a young man you volunteered to be a jet pilot in the Korean war. Did you look at the world very differently then?

Well, I'm not necessarily a warmonger, but I'm not necessarily someone who would want to sit around while we were getting the shit beat out of us either. I'm a second-degree black belt in taekwondo and also kung fu, so I'm a martial artist and I'm not afraid of trouble. I just don't like to look for it.

You fell out with the church in the 50s – unlike artists such as Elvis and Jerry Lee who kept trying to balance the devil's music with the love of God. What happened?

I was teaching Sunday school and playing clubs, but there were a lot of members of church who didn't think that was a good idea. They felt if I was going to teach Sunday school I should quit my job at the club. I was playing music on Saturday night at the Nite Owl to a lot of the people I saw in church on the Sunday morning. I wasn't the only one going to both places. (3)

Did starting to smoke weed (4) make a difference to the way you thought about the world and your political interests?

When I was out in the bars drinking and fighting I was a little bit less of a peacemaker than I would be if I'd had a coupla hits of a joint and gone and laid down somewhere. I'd have less bumps on my head, that's for sure.

Won't it be too hard for Congress to decriminalise weed?

Well, Connecticut just became the 17th state to legalise or decriminalise marijuana (5). It's coming. It has to, because economically we need the money – why give it to criminals? Most people realise it's not a deadly drug like cocaine or cigarettes. Cigarettes killed my mother, my dad, half my family, so don't tell me about health when you're talking about legalising marijuana because it's not dangerous healthwise. I'm the canary in the mine, and I'm still healthy. Had I stayed with alcohol I would have been dead or in prison or somewhere today. (6)

Do you think the policy-makers in Washington might one day realise the war on drugs has been lost?

I do know, again, there's a lot of money in prisons and there's a lot of money in lawyers, and down on the borders there's a lot of money in guns that come back and forth because of the drug laws. If we made everything legal we would save a whole lotta money, a whole lotta lives. If we taxed and regulated the drugs the way they do in other parts of the world, we would be far better off, I think.

Have you been disappointed with the Obama administration

When he was running for office and he had a lot of aspirations, I had a few doubts about whether he was going to be able to do it or not. I don't think the president has as much power as we think he does, and he can say what he wants to while he's running for office, but once he gets in there, there are four or five guys who take him into a small room, sit him round a small table and say: "Look, cowboy, here's the way it is." I don't believe he can do everything he said he would.

Is songwriting a gift or craft?

It's a gift. It all comes from somewhere. I started out really young, when I was four, five, six, writing poems, before I could play an instrument. I was writing about things when I was eight or 10 years old that I hadn't lived long enough to experience. That's why I also believe in reincarnation, that we were put here with ideas to pass around. Somebody sent me here to write Crazy (7) and gave me the talent to do it. I can't take credit for any of that.

Footnotes

(1) One of the first great country musicians, as founder of Bob Wills and the Texas Playboys in the 30s.

(2) One of the other great country singers, nicknamed the Cherokee Cowboy.

(3) Willie maintains a relationship with God, via a portfolio kind of spirtuality.

(4) Nelson is a proud and inveterate weed smoker. As recently as November 2010 he was arrested for possession, but the prosecutor agreed such a small amount for personal use merited only a fine. The small amount in question was 6oz.

(5) Connecticut actually decriminalised marijuana in June 2011. Maybe he meant New Hampshire, which did so in March 2012.

(6) It would be fair to say this is the subect on which he was most effusive during the course of our interview.

(7) Sung by Patsy Cline, and reputedly the most popular jukebox song in history.

• Willie Nelson's new album, Heroes, is out now on Legacy.