I did this.
I knew I needed to do something about my level of fitness, and despite doubts, I went for C25K (I though that everyone who posted positively about in on MN was secretly the sporty girl at school - I never was, and was convinced I was the wrong shape to run, and had a heap of other sceptic thoughts)
But I did it, as a kind of prescription to myself. Something to be ticked off the "to do" list. A necessary chore (like several other necessary chores, to be done because it was required; so it didn't matter if I liked it or not, it just needed to be done)
And that was how I stuck to it. A necessary evil. Which I could feel was doing good. Logging progress helped (Strava)
Even when I'd finished C25K, I kept going, running 3x a week and seeking the odd new challenge
It took about 9 months+ to start to enjoy it. I joined a running club, did parkruns and entered the odd event. And then really enjoyed it.
I think the key part was seeing progress. Didn't matter how little, or how long it took at see any at all. There was a real sense of achievement
I don't think I could do a handstand though - but used to do all sorts of flips when I was a girl. Working to recapture youth, by strength training and then doing the things you used to love, might be a satisfactorily nostalgic thing to try. Skipping? Elastics? That ring/string/ball jumpy thingy?