The 33-year old Swedish midfielder played 70 minutes of the Hoops' 1-0 win over St Mirren at Celtic Park on Saturday and although he wasn't at his best, he admitted that he felt good and is expecting plenty of improvement for the final stage of the current campaign.
"It was great, it felt amazing to be out there playing. I've been waiting a long time so it felt great," he said.
"It's been frustrating not to play more but I have always had dialogue with the manager, which I understand.
"He wanted me to get fitter and when I was ready to play I picked up an overload in my calf because I had been doing extra running after training.
"That kept me out for another three weeks.
"He wanted me to play at Inverness when the game was called off. It would have been my first game in the SPL so that was frustrating.
"Thankfully I got my debut against St Mirren and I feel great. I haven't played 90 minutes, but I'll get that when I start to play more."
Ljungberg says that playing injured is something he has had to deal with throughout his career but says it holds no fears as he achieved success with Arsenal whilst carrying some problems.
"I remember when we won the Double at Arsenal, I broke two ribs and my ankle," he added.
"I was out for a few months, but I came back around this time and scored seven in eight games and we got the Double. We had a couple of players who came back and that helped improve the team. You need to have that belief and ability to handle the pressure.
"If you drop a few points now, you might lose everything you have worked so hard for throughout the season. "It's important to stay calm and to believe in what you are doing."