Rockclimbing might be another good and fun option, and can be done by yourself to some extent (bouldering, or borrowing gym staff). For me, it has an added bonus since lots of mathematicians socialize by rockclimbing together.
Rockclimbing might be another good and fun option, and can be done by yourself to some extent (bouldering, or borrowing gym staff). For me, it has an added bonus since lots of mathematicians socialize by rockclimbing together.