Joe Hart knows time is no longer on his side - which is why the Celtic goalkeeper is desperate to learn everything he can under Ange Postecoglou.
The Hoops boss picked England's former number one off the Tottenham bench last summer and backed him to show the form that saw him claim Premier League glory with Manchester City earlier in his career, and two more trophies were added to Hart's glittering silverware cabinet as Premiership and League Cup crowns were claimed.
Postecoglou's non-stop mantra was a big plus for the 35-year-old after a tough few years following his exit from City. Turning 36 this season, Hart is well aware that there's only so long he will be able to carry on for. It's fuelling his desire to help his team claim more success as pre-season gets underway for the new campaign, telling Celtic TV: "I don't think we can get away from the fact that the only reason we had success last year was because we were united.
"It was because we worked so hard. The manager made that point every single time. Whether we ground out a 1-0 or won 7-0, the analysis after was how hard we worked. It was how hard we pushed each other, how we didn't give the opposition a chance to breathe. The moment we step away from that is the moment we don't come back from pre-season happy.
"We come back because we are having to re-establish something that happened in the past. I am super aware of it and that comes with age. That comes with me knowing full well I've not got as long as I once had in the game. So I'm going to to try and take every little thing I can from it.
"I love football and the opportunity to play. I have really enjoyed being here and we are back at it. Hopefully we have another good year ahead."
Hart will compete with Benjamin Siegrist for the number one slot this campaign. The Swiss stopper has arrived from Dundee United and bolsters the ranks between the sticks alongside Scott Bain.
Champions League group stage football awaits Celtic this season and their title defence kicks off against Aberdeen later this month. First they will embark on a pre-season camp in Austria.
