Personally, I read, write, practice my Welsh/French, listen to music, edit videos, play basketball/soccer, or play old PS1/PS3/Dreamcast games. I would suggest if you're going to learn a language, though, to pick one that will be useful later in life; I chose French because I plan to move to French-speaking Canada, and I chose Welsh mainly for fun (and as such I don't practice as much), but partially because some of my family are from Wales.