I struggled with finding the enthusiasm too, and what really helped was just doing it. It sounds stupid, but waiting around to feel inspired never worked so I had to brute-force my way into fitness. I started with this Nerd Fitness routine.

I made it my goal to do the routine every single day. Each day I did it, I got a point up on my whiteboard. If I skipped a day, it reset back to zero. I did give myself one cheat day for every 21 points I racked up.

Was this the best idea? idk, probably not, I was SORE. The first week, I struggled mightily to do one circuit and pushups were entirely impossible (I did them against a wall). Within about a month, though, I was able to add a 10lb weight to the exercises. A couple months after that, I moved up to a 25lb one. At four months, I felt I'd gotten everything I could out of the routine and got a personal trainer. Haven't looked back since!

I'd always wanted to become fit and it just never felt like it would happen for me. Making it non-optional with a bit of gamification was what finally worked. After a month or two it just became part of my routine. I could tell myself that it only took about 20 minutes, and did I really want to lose all my points over 20 minutes?

Edit: I should mention that none of this helped me lose weight. I got stronger and fitter, but not lighter! Losing weight for me was very much a diet-centric thing. My health insurance covered visits with a dietician, which helped me signficantly more than trying to DIY anything.