The Irish defender was his national side’s man of the match against Hungary after being recalled to Stephen Kenny’s side for two friendlies this month.
It was the first match action for the Brighton defender since February and the experienced stopper had not featured since Neil Lennon left Parkhead.
Now Duffy is hoping “that’s the bad bit over” and he can kick on next season to build on his appearances for the Republic – and thanked his manager for the refresher in how to play football again after so long on the sidelines.
He said: “It’s always tough when you go through a tough spell and I think most footballers do in some part of their career.
“I’ve gone through it, I’ve got a great manager here who trusts me.
“I’ve got no complaints about not playing in the team. I’ve tried to play my role and help the younger lads.
“I haven’t been playing football, so I have total belief and thanks to the manager for giving me a game first and foremost.
“I enjoyed it again, I sort of forgot what it felt like to play football.
“Hopefully that’s the bad bit over and a little rest and I’m ready to be back next season, kick on and show everyone how good I am.”
Duffy was heralded as a major coup for Celtic last summer, joining on loan from Brighton, but the deal was a disappointment with fluctuating form leading to the defender falling out of favour.