Basically follow the same healthy habits you would employ if there were no lockdown. asanelderly geezer, I have been staying home for the last several days. I have been exercising (yard work and a stationary bike -about 45 minutes a day). I try to eat healthy stuff and lay off the booze (easily accomplished).
If I didn't have the bike,I would run or walk around the neighborhood - just maintain social distancing.
This is also a good time for those rainy day projects...
@georg3441 this is a question is top of mind for many of us right now. It's likely you'll get lots of good suggestions, like those from @hikermor. In addition, here's a new blog we put together with ideas on how to stay fit while working from home...pretty applicable advice!