The Parkhead midfielder stayed behind after most of his team-mates had jetted away on their summer breaks to finish his rehabilitation from the hamstring injury he suffered against Rangers in April, which ruled him out of the run-in.
Ledley, who enjoyed an impressive debut season in the SPL, wanted to make sure he had made a complete recovery from his injury before going on holiday.
He said: "I've been doing a lot of treadmill work and moved outside to do some running recently. Everything is going well and I'm ahead of schedule so I just have to keep doing what I'm doing.
"My fitness is high and I'm grateful everything has gone well. Normally grade-two hamstring injuries take six to eight weeks so hopefully in just under eight weeks I'll be fine.
"Everyone's left and it's only me and Shaun Maloney that's around, so I'm looking forward to my holidays now.
"The boys come back in the middle of June and I'll get an extra four days off, but that's it.
"I might be going to Vegas with my mates, but I haven't booked it yet. I'm going to Portugal for two weeks, though."
Ledley also admits he is looking forward to starting pre-season without the extra stress of having to get to know his new team-mates.
Speaking in the Celtic View, he explained: "Last season, I met everyone for the first time at Heathrow and headed over to America with them from there.
"It was hard because I couldn't exactly go along the plane shaking everyone's hand so it was difficult at first.
"I was rooming on my own as well, which probably made it a slower process in getting to know everyone.
"I had to sing a song on my first night as did the rest of the new lads, but I only lasted about five seconds."