Since you bring up side projects, I used to put so much pressure on myself to always have at least 1, if not 2, side projects that could be money making. In the last 5 years, I’ve given that up. The pressure, after work was done for the day, to be productive for 2 or 3 more hours was just “killing” me (slowly - I wasn’t exercising. I was eating fast food so I could get back in front of the computer). So I went cold turkey. If something is interesting, I’ll read about it. If it causes an itch, I’ll scratch it. But I don’t put any pressure on myself for set amount of time to look at it. 5 minutes one day, 2 hours the next. Doesn’t matter. As for the feeling of working on something better? I have that to. If something more interesting pops up, I move my time to it. But for that to work for me, I had to come to terms with that I’ll probably never finish anything. And that’s OK for me. I have plans for apps all the time. But the 2 that I actually built to completion? A budgeting app (when Simple bank shutdown) and a barbell app (calculates my warm up sets for me and which plate combinations to use).
Physically: Get a primary care physician. Get blood work and a physical every year. If you end up at urgent care or something else outside of your PCP, send them the records. If you like data, there is something magical about looking at your past blood work results and watching your diet and exercise change those numbers.
Move more. If you’re doing absolutely nothing, start with walking. Just you. Rain or shine. Cold or hot. Everyday. If you can make a habit out of walking, other physical habits are easier to form. I take 2 walks every morning. The first is with my incredibly skittish dog. We don’t walk far or fast. After I return her home, I go back out for my walk. Just me. No podcasts. No music. Just a brisk 1 mile every 15 minutes for 30 to 45 minutes. But don’t start there. Just go our your door, walk 10 minutes and turn around and walk back. The next day, add a minute. Don’t worry about distance or pace. Just get in the habit of going out your door and walking. Once I developed the habit for walking and learned to love how walking made me feel, I started adding simple workouts - push-ups and air squats. Eventually it lead to barbells. Your journey might go in a completely different direction. And the only other piece of advice I can give you - don’t follow fitness people on Instagram or YouTube (or any other social media). Those 30 second clips are their BEST workouts. They don’t show you the years of training they endured to get there.