British number three Tim Henman says he has no intention of retiring at the end of the season.
Henman was ranked five in the world last April
Henman has slipped to 63rd in the world rankings, leading to speculation he might quit at the end of the year.
But the 31-year-old told BBC Radio 4: "If I wasn't enjoying it and feeling I was able to compete, then certainly it would be time to assess things.
"But right now that certainly seems a long way off and there's no reason why I can't play a good few years yet."
But he ruled out making a return to Great Britain's Davis Cup squad if Andy Murray was forced out of the team to face Serbia and Montenegro because of illness.
Henman, who retired from the Davis Cup in January, said: "It's a crisis situation which doesn't include me. I'm not going to change my decision on the basis of someone else's health."
And he does not expect to make a comeback in the future, despite captain Jeremy Bates' efforts to persuade him to change his mind.
"He's always kept the door open for me and likewise I'd never say never. But I'd be very surprised if I play Davis Cup again," he added.
Henman was fifth in the world in April last year, but his ranking has tumbled following a frustrating 12 months.
He has been hampered by back and shoulder injuries and fallen behind Andy Murray and Greg Rusedski in the British standings.
"There's no doubt it's been a difficult 15 or 16 months and that's been probably dominated more by back problems than my results on the court," Henman said.
But he showed glimpses of his best form in beating Marat Safin and Lleyton Hewitt in consecutive matches at the Nasdaq-100 Open - before losing to German qualifier Simon Greul - and now feels his luck is turning.
"In the last couple of months I've really felt like I've begun to turn the corner," he added.
"I've felt healthy on the court and that puts a totally different slant on everything.
"When you can practise and train properly and actually enjoy what you're doing it's going to have a knock-on effect on performance."
The Briton was speaking before he launched the Ariel Mini Tennis for Schools programme, a nationwide initiative to make the sport more accessible to British children.
All primary schools in Britain have been given the chance to take part, with 100 of them then selected to participate in the scheme.
Tennis equipment and coaching will be made available from the Lawn Tennis Association, which is working alongside teachers to generate more interest among pupils.
Each participating primary school will be handed enough equipment - including nets, racquets, balls and bags - for 50 children to use in environments such as playgrounds, parks and gym halls.
Henman, an ambassador for the initiative, said: "Supporting tennis in schools at grass-roots level will help us to nurture and develop tennis talent in the children of Great Britain."