Exercise

Actually, starting with something manageable (but a small challenge) is perfect, IMO.

It's IMO the best way to build fitness (as long as one progresses the duration, intensity, frequency or type of exercise over time to keep that manageable challenge in the picture as fitness improves).

It's also good from a health and weight loss perspective. For health, exercise is a "good stress", but overdoing can shift the balance toward putting too much physical stress in one's life, especially when a calorie deficit (another physical stressor) is happening. All-source stress is cumulative, so managing total cumulative physical and psychological stress is a good plan.

On the weight management front, I'm not a big fan of creating a calorie deficit via exercise (YMMV), but regardless of how one thinks of that, doing too much exercise too soon is exhausting, and can reduce the calorie burn from daily life activity: Counterproductive. What I mean is that working out to exhaustion causes fatigue, and fatigue makes us rest more, perhaps in subtle ways: Less spontaneous movement (like fidgeting), maybe deferring high-effort home chores, finding active non-exercise hobbies (gardening, playing a musical instrument, window shopping, etc.) less enjoyable so doing them less, and that sort of thing. The net calorie burn, once fatigue impact is figured in, might be less than anticipated.

On top of all of that, enjoyable exercise tends to become a habit, while miserably difficult punitive-feeling exercise tends to drop out of rotation at the slightest excuse.

I think you're doing great!

Awesome, at least you've gotten started! That's more than a lot of people ever do!