People add their personal interests and hobbies to their resume to appear well-rounded and interesting. As a hiring manager I can tell you right now that 99% of the time I don’t give a shit about your hobbies.
You’re sending me your resume to get a job. So make sure every single thing on your resume helps you achieve that goal. If you do include a hobby it must help further your objectives and not simply serve as filler or an attempt at humanizing yourself. I know you’re human. I know you probably have a life outside of work. Unless what you do outside of work makes you better at work I don’t really care.
How do you know if listing your hobby helps further your career objectives? First consider the skills and characteristics the hiring manager is seeking. Leadership? Then list how you spearheaded neighbourhood cleanup efforts.
Or use your hobbies to show how you are gaining experience you haven’t been provided during your 9-5.
Or use your hobbies as a way to craft your personal brand. You want to be seen as a self-starter? Then list personal interests that show that.
Unfortunately, most people take a passive, superficial approach to listing personal interests on their resume. They literally list personal interests: cat herding, unicycling, circle-research. Great, but irrelevant.
If you do include personal interests on your resume, ensure they are there for a purpose.