The Celtic player received the same warning from Stanley Menzo, the manager of Lierse where Watt is spending a period on loan, although Stark hopes that the spell in Belgium will emphasise to Watt the need to apply himself to all aspects of being a professional footballer. "It's something that's been highlighted first by the Lierse manager Stanley Menzo and Neil Lennon was then forced to comment on it," Stark said.
"Neil expressed disappointment that it was made public and I can understand that, because it's Neil's player and you would never really do that. But because Stanley has made it public, I'll address it too and he does need to work on his fitness. Every time he's come to us he's flagged it up to us that his fitness isn't what it should be. It's very difficult for us to help him gain that fitness."
Stark will speak to Watt, who has scored already for Lierse, and is adamant the player can adapt to the demands of the game. The under-21 manager raised the example of Robert Snodgrass, who realised the changes he need to make to his approach and is now one of the leading Scots in the Barclays Premier League and a full internationalist.
"It's human nature that you get boys who have problems they need to overcome," Stark said. "Tony came into the game late, and he's got stardom pretty early with Celtic. That's difficult for a young boy to handle. But I want to help the boy to develop and sometimes they need a knock, if you like, to show them they need to be doing more.
"It's about personal responsibility. We've all been there as teenagers and you want to have a good time and enjoy your life. There's no better way than being a professional footballer but sacrifices need to be made."