Spending Time In Personal Development

With all the extra time I have, due to the pandemic, I have been wanting to try some new things in my life. It is kind of like a time to redefine myself. Ultimately, I have narrowed down my possibilities to three things: learn a new instrument, focus on an author's works, or prepare for running a half marathon. I think they all have their benefits, but I would love to hear from some of you what you think is best. Put something in the comments if you have a better thing for me to do.