I've always had trouble sticking to a consistent workout routine throughout the years. But during the beginning of 2022, I was experimenting a bit and tried doing 5 sets throughout the day instead of the more traditional shorter rest periods. My rest would be pretty much 90+ min intervals (sort of my breaks in-between focused work). It started with just air squats, then slowly progressed to a whole body workout where I do the following for each set:
1. Push ups
2. Air squats
3. Crunches
4. Dumbbell bicep curls
5. Standing dumbbell shoulder press (way harder than sitting and better for your back)
6. Dumbbell side lateral raise
7. Dumbbell bent-over row
I specifically didn't mention the weight because it's not important for you to compare that. However, I will say that I prefer lower weights combined with high reps (e.g. 15-20) because my goal is to build both strength and endurance for daily living.
I used to think that you needed to have really short rest intervals (e.g. 2-5 min) in order to build muscle. But you'd be surprised at how well the results can be, especially if you do this every day, which is totally possible because you generally won't feel sore from exercising this way. It's also easier for more to stick to this routine because just doing one set lowers the pain of starting for me, but you might feel differently about it.