From prison to the Premier League in the space of a year. Some may say that Troy Deeney's lags-to-riches story will be given a happy ending if Watford win at Wembley on Monday – but not Deeney. The striker is contrite, not trite. Victory would bring joy but no conclusion.

Life remains a work in progress, but big progress has certainly been made so far by a player who missed the first meeting of Watford and Crystal Palace this season because he was locked up. "It was probably the best thing that could have happened to me," he says.

Last June, a few days before his 24th birthday and just a few weeks after cancer claimed his father at the age of 47, Deeney was sentenced to 10 months' imprisonment for affray following a night-club brawl in which he kicked a student in the head. "Just so you know, they all know who you are," the wardens told him as he was led into Winson Green prison in Birmingham. "Oh shit, this is cold," Deeney remembers thinking on his first night inside. "I had one blanket, not even a blanket, a sheet. The bed was caved in. I spent the first two days moping." Then he started to get himself together.

He got a job in jail, cleaning the landings. "You didn't have to have a job but I chose one so that I didn't go brain-dead. Otherwise you'd just look at the same walls and drive yourself crazy." The other inmates gave him neither special treatment nor intimidation, but were puzzled by him: "You've got a good thing going in life, how did you end up in here?" they used to ask. Deeney asked the same thing.

"I had months to ask myself: 'Why did you do it?' I have answered them questions for myself," he says. He found explanations, not excuses. The death of loved ones was a factor but so was the thoughtless way he was living. He realised he had to change, especially for his three-year-old son, Myles.

"My great nan died just before, then my dad died in May so at that time I had a lot going on but I also got to realise there is no excuses for what I did so you get to that point where you think: 'You know what? Is it really worth going out and drinking and basically wasting money? My dad had always worked hard to make sure that I had nice stuff and he died at 47 so I just want to make sure that if something like that happens to me, my son would have everything ready.

"I'm not going to say I'm thankful [for being jailed] but I'm glad that I got to see the opposite end of the scale. I have grown up massively. I nearly went broke so that was a massive thing as well. I save money and stuff now, I don't drink. It is a case of making sure that my partner and my son never have to go through all the stress they went through, because when I went away nobody saw what they had to deal with because all the bills still come through and I wasn't getting paid so she had to cope with all that."

After two months in Winson Green he was transferred to Thorn Cross open prison in Warrington. An upgrade but no bed of roses. "You have your own key to your own cell. It was more relaxed but there were also more rules. For example, if you came out after 8.30pm, even going to the toilet, that's a strike against you and if you get two strikes you get shipped back to a normal jail."

He got a job cleaning the gym there, and was allowed to use it for an hour every day, a perk that enabled him to stay fit – not that he thought Watford would take him back when he was released. Especially as the club had embarked on a revamp, with the new Italian owners recruiting high-quality players from all over Europe. "I had no contact from Watford while I was inside," says Deeney. "I was just reading papers like everybody else. They kept signing all these players and I was thinking I had no chance."

After serving four months he was released in September and went to speak to Gianfranco Zola for the first time. "I was apprehensive because everyone knows who the boss is – a really well-spoken guy who everyone loves. Him and me were at completely different ends of the scale so I was a bit worried he might not like me. But we had one conversation when I got back and he said he'd seen me play a few times and said I reminded him of Carlton Cole."

The manager originally planned to watch Deeney train for 25 days before considering him for selection – but 10 days later he gave Deeney his comeback as a substitute against Bristol City. "He was too good," says Zola, who started the striker in the next match against Huddersfield Town, where Deeney scored the first of his 20 goals this season.

He is in the most prolific form of his career. "When I came out I gave myself a kick up the backside and really dedicated myself to being a better person," he says. "I lost a stone and a half. My body fat went down from 11% to 8.1%. I'm grafting and taking chances. I used to do it in training but when we'd go out on the pitch I'd be very cautious, safety first. But now I've let go of that. I don't fear missing. I just know that if things go bad, it's not going to be any worse than it was."

And if things go well on the pitch, that does not automatically make people great off it. "There's much more to life than football. If I play at Wembley and score I will be a hero, but I am still normal Troy, making mistakes and trying to learn and improve on a day-to-day basis."