Andy Murray says Britain's youngsters need to have more focus if they are going to have any success in tennis.
Murray's comments come after the LTA suspended juniors David Rice, 18, and Naomi Broady, 17, for "unprofessional behaviour" following a BBC 5live probe.
The British number one said: "Everyone goes through a phase like this - I made mistakes at 16 when I was in Barcelona.
"But now I don't drink, I don't smoke - it's the sacrifices you have to make if you want to become a great athlete."
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Murray told BBC Sport: "It's just something as a professional athlete you have to realise; you're not at university, not doing a nine-to-five job, you have to stay in tip-top shape.
"Being professional is the main thing that you need to get right. If you don't have that then you're never going to make it."
Rice, the second-best British junior, and Broady, the national Under-18 champion, have had their funding withdrawn after they were deemed by the LTA to have breached contracts requiring them to act professionally.
The LTA took the action after being alerted by the BBC to photos and confessions on the Bebo social networking website.
"Guys like Andre Agassi and Jim Courier went through some difficult times as well... fortunately they were monitored pretty closely"
The duo are believed to have had funding and coaching withdrawn and several other British junior players have been warned about their future conduct.
Meanwhile, American coaching guru Nick Bollettieri told 5Live that the situation provides a tricky problem for LTA chief Roger Draper.
Bollettieri, a former mentor to Andre Agassi, said: "Guys like Andre Agassi and Jim Courier went through some difficult times as well.
"Fortunately they were monitored pretty closely - but some got out of line as well and we were able to curtail it.
"This is not an easy situation for Roger Draper and the decision he makes now on which direction he goes will have a major impact on the entire programme."
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