The Frenchman has not been on the pitch since December last year after he picked up an injury in the 3-0 win against Dundee United.
He has since spent much of the year in France undergoing rehabilitation and managed to return to Glasgow only on Thursday to work on his return to action.
The 28-year-old admits that watching Celtic toil without him was tough as he wanted to be able to help his team-mates, but now he is focused on making sure he is fully fit and ready to make an impact in the upcoming season.
“I’m feeling good”, Jullien said in an interview with Celtic TV.
“In the last session I did in France I was starting to run on the pitch like I was before so I was really happy with that.
“I just need to keep going and work on getting my strength fully back.
“I can’t wait to be back on the pitch with my team-mates and to have that feeling with the ball again.
“It feels like something is missing and when you see your team-mates playing football and you’re unable to do anything it hurts.
“Just thinking of coming back and enjoying football again is a feeling I can’t wait to have.”
Jullien will be looking to impress Celtic’s new manager, likely to be former Australia boss Ange Postecoglou, when he returns to action.