What Happened?

Start by figuring out what the hardest thing was for you. If you think improving your diet is the priority, what about that is causing the most trouble for you?

I can only speak from experience. For me, I was eating 3000 to 4000 calories a day. Obviously gained back everything I lost eating that much, so what I focused on was getting it down to 2500, then 2000, then 1700. Now I'm uncomfortably full on over 2500 calories. Next was exercise. My body was so stiff, I got started just walking 20 mins 3 to 5 times a week. Now I have to workout an hour 5x a week or my mood suffers. Weird.

Start small, start at the area that's your highest priority. If you want to cycle again, maybe make it a goal at first to cycle for 10 mins a few times a week and work your way up. If you're no longer passionate about it and just want to move your body, maybe get to a park, walk to run small errands, go to gym and use the pool. The point is: no matter what you do, any small step is better than nothing and they add up over time. 😊

Have you been screened for depression? It sounds like you might have overtrained with the cycling, which can cause burnout and a lack of interest, but it could also be a mood disorder.

Leaving aside a medical problem, I think the best way to get back into a healthy way of living is to make it a habit. Start doing some physical activity every day, ideally at the same time, though don't push too hard at first or do high-impact activity like running more than a few times a week. Look at your diet and decide what changes are most important to make immediately, but don't change too much.

Motivation is overrated. I run, cycle, and hike not because I'm motivated to do so (I am some days but not all the time), but because doing something outdoors has been a habit of mine for years, and I feel unhappy when I don't do it. If I relied on motivation, I'd be a lot less active--which was the case for my first several years in my current job, when I had a lot of stress and didn't make the time to exercise.