Most people believe their job is hard. In most cases, it is. The difficulties presented by each job are different, and we acknowledge that to each other. We think about the skill set involved and say "I couldn't do that". Few jobs, however, are as misunderstood as that of a professional actor.

Part of the underestimation is rooted in a basic view of acting as "the art of lying". It is quite the opposite. Great acting is the art of telling the truth and telling the truth can be exhausting. But here's the rub. Great acting should also look effortless, natural and easy. And so, it is often misjudged as actually effortless, natural and easy. We recall our fond experiences of school theatre or amateur dramatics and think, "I could do that". It is like comparing the enjoyment of riding one's bicycle around a park on a sunny day, to the life of a professional cyclist.

Having had many jobs – and most actors have had many jobs – it is by far the most difficult. The part we share with you in the theatre or on film is the fun part. And that is as it should be. However, the part you don't see – the preparation, the mind-numbingly dull vocal and physical warm-ups, the Monday to Saturday rehearsals, followed by evenings of learning lines or working in a pub, the constant disappointment and rejection of auditions, the emotional self-abuse which comes from exploring fold after fold of oneself –that hidden part, forms 95% of life as a professional actor.

I have worked 14-hour shifts in a travel agency, seven days a week, for six months during the Greek tourist season, with no day off. I have handled multi-billion industry investigations as a competition expert, with days and weeks which I thought would never end. None of it compares – not even close – to the self-imposed temporary obsession that preparing for a part demands. The sleeplessness that comes from working days for four weeks then nights for four weeks or, if you're lucky, both. And all this usually for minimum wage or, often, no money.

A few years back I was lucky enough to play Othello. People would come up to me after curtain-down and say "how did you manage to learn all those lines"? Learning lines was the easiest part of the process. Going from a place of complete devotion to one's wife to absolute murderous intent, within a 20-minute scene, was quite a bit harder. Walking through the choreography of strangling a fellow actor, a thousand times so that you can then do it for real every night, was quite a bit harder. Doing it, while noticing her distraught mother in the front row half-jumping out of her seat, was harder still.

I have been rehearsing a play for the last month. Hamlyn, by Juan Mayorga, is based on real events and concerns a suspected ring of paedophiles in Spain. How does it feel to rehearse a scene in which I am being interrogated by the police as a suspected pederast? Well, on a good day, when it all comes together and everyone is firing on all cylinders, it feels like I was interrogated by the police as a suspected pederast. And then I get on the bus and I practice lines in my head and play out scenes in my mind, grimacing, and as I notice that people around me are staring at me, I realise that I am in floods of tears. That is the job.

I am not griping. Along with all the difficulties, the rewards are enormous. No, not fame and fortune – if I wanted that I would buy a lottery ticket and have a much better chance. I mean the ability to create something out of thin air, to imagine a warm summer night and make people inside a warehouse in the middle of winter believe it; the chance to touch souls and make you think.

Most of all, the hush that occasionally falls over an auditorium, described by Shelley Winters as "the sound of a wonderful, deep silence that means you've hit them where they live". I simply share these thoughts because they formed, for me, a lesson well worth learning: that the road to "easy" is often very hard.

• The UK premiere of Hamlyn, by Juan Mayorga, opens in the Space Arts Centre on 22 April