Healthy maintenance

Without knowing more about you, the generic answers would be two things:

1. Gradually work your way up to recommended levels of exercise for general health, at minimum, starting where you are and doing enough to create a manageable challenge. As you get fitter, the activity will get easier. As that happens, increase the activity to keep a manageable challenge always in the picture. ("Increase" can mean duration, intensity, frequency, or type of exercise.) "Manageable" avoids over-fatigue, under-recovery, and potential for injury. "Challenge" creates fitness progress.

"Recommended levels . . . for general health" are 150 minutes weekly of moderate cardiovascular exercise, or 75 minutes weekly of more intense cardiovascular exercise, or a proportionate combination, ideally spread over at least 5 days of the week; plus at least 2 days a week of strength training. Like I said, though, work your way up to that if you're de-conditioned or recovering.

For cardiovascular exercise, pick one(s) you enjoy, ideally . . . at least one(s) you find tolerable and practical. There are literally dozens of options. It doesn't have to be some gym machine, or the same thing every time. Examples: Walking, biking, swimming, canoeing/kayaking/rowing, skating, skiing, frisbee golf, basketball, pickleball, tennis, martial arts, various kinds of dancing, physical VR or video games etc., etc. etc.

Strength exercise can be bodyweight stuff (calisthenics, for example) or weight lifting, and more.

2. Get overall good nutrition, on average, at appropriate calories. This means a reasonable minimum of protein, healthy fats, fiber, micronutrients, pro- and prebiotics, and of course adequate hydration. In general,less processed ("whole") foods will serve you better than highly processed foods or supplements. Again, choose foods you enjoy, plus find affordable and practical. You don't need specific "diet foods", "health foods", or "superfoods" . . . just good, nutrient dense, calorie appropriate regular foods like meat, fish, veggies, fruits, nuts, etc.

This needn't all be perfected at once. Just keep chipping away at improving both exercise and diet. That'll be fine.

Also, have you taken a look over in the Goal: Maintaining Weight section of the MFP Community? There are quite a few threads there where many people share their maintenance strategies. You might get some ideas there. Here are a couple of example threads:

https://community.myfitnesspal.com/en/discussion/1422943/long-time-maintainers-how-do-you-do-it/p1
https://community.myfitnesspal.com/en/discussion/10008273/maintainers-how-do-you-keep-your-head-in-the-game/p1

Wishing you success!