London:Britain's Andy Murray may have beefed up his physique but he insists it is his new-found mental strength which makes him a definite Wimbledon title contender.
World number three Murray has transformed from a wiry teenager who collapsed on court vomiting into a muscular 22-year-old who can last the distance in five-set Grand Slam matches.
But the Scot, who is preparing for next week's Wimbledon championships, said his physical development has given him the mental confidence to believe he can win every tournament he enters.
"The physical side has made a huge difference to the mental side of my game," Murray said as he launched his new Fred Perry-designed Wimbledon kit in London.
"When I wasn't in my best shape when I was younger, you go into matches with doubts, not knowing whether you can necessarily last the whole match and if you lose the first set, you know you might not be able to come back.
"When you spend a lot of time in the gym suffering it makes playing tennis feel a lot easier.
"Now I go in with a clear head and no excuses or doubts in the back of my mind. It's not like I've been to see a sports psychologist or anything, it's just working really hard off the court makes a big difference on it."
And he said: "Since Wimbledon last year when my game kicked on a lot I started to improve big time. I have that belief that I can play the whole of the slams now.
"I put a lot of pressure on myself and I expect a lot of myself in the big tournaments, and that helps me play better."
No British player has won the Wimbledon men's singles since Perry in 1936 and with Tim Henman and Greg Rusedski retired, Murray must now shoulder the weight of national expectation alone.
But the annual storm of hype that usually besieges the British number one at Wimbledon has been whipped up even more by Murray winning the Queen's Club championships, the main grass court warm-up event.
In beating the USA's James Blake 7-5, 6-4 in west London on Sunday, Murray became the first Briton to win Queen's since Bunny Austin in 1938.
But he vowed he would not let the burden of Britain's 73 trophyless years since Perry get to him at the All England club.
"A lot of people, ex-players -- I don't mean Tim and Greg -- use it as an excuse as to why a Briton hasn't won Wimbledon for so long but I don't feel it makes any difference once the tournament starts," he said.
"If I ever need advice, Tim will always be there for me. We chat a few times a month and always keep in touch. But when it comes down to dealing with pressure and expectation in big tournaments, that has to come from within.
"It's easy to get caught up in all of the hype and everything that goes on. But I will prepare the same as I do for all the big tournaments. It is difficult but you learn each year."
And he said: "I think I can win it, but I'm going to focus on the very first match. There's no point in me thinking about winning the tournament now before it's even started.
"I would love to win Wimbledon one day, there's no question about that, but I don't think about it too much.
"I could easily lose in the first round if I have an off day.
"But hopefully I can do it."