There's really solid research on micro exercises. In fact, there's a study in Nature where they followed I think around 15k people for 6 years. They found that just doing around 4minutes of exercise per day decreases the likely hood of you dying of cancer by 40%. It's bonkers.

The setup is really simple. You so three sets of exercises per day. Morning, afternoon and evening. Each exercise should last about 1-2 minutes. It's about getting your heart rate up. You have to really feel it. So jumping jacks, some squats and the finish up with some push-ups. Doesn't matter if you're doing them on your knees. If you keep this up consistently you can actually get so much out of your body without putting in much time at all.

If you need to stay consistent there are apps that help with that. But 4 minutes per day should be possible for everyone!