@tvdv grinding by hand can be considered exercise though, and depending on the amount you grind you could absolutely add it to your day’s activities I got one a few months ago to slow down my coffee consumption: it works.
@thibautsailly sure it’s exercise, but it’s not remotely comparable to a session on an elliptical trainer! I started buying beans and grinding by hand all over a decade ago for the same reason, fwiw