Well, for me it's contributing and maintaining packages for FreeBSD it's simple and fast to start and a lot of fun (for me).

1. Open a account on https://bugs.freebsd.org/bugzilla/

2. Find outdated ones https://portscout.freebsd.org/

3. Open a bug-report with diff to update port(package)

4. Read https://docs.freebsd.org/en/books/porters-handbook/

5. Port new software and have fun.

Thanks for giving back time and energy, have a great day!

Edit:

I forgot, if you want some exercise in nature refine/add OpenStreetMap-data with https://josm.openstreetmap.de/ and/or https://wiki.openstreetmap.org/wiki/Upload_GPS_tracks