[Sun Care] Do we need to reapply sunscreen every 2-3 hours when indoors AND when we don't sweat?

Beauty Tips For Body Care
I'm especially looking for personal experiences. It's not that hot in my city yet so I don't sweat. I work from home and spend 45 minutes outside in total (half in the morning, half in the evening). I use a zinc oxide based SPF 30 sunscreen. I put it on in the morning and not re-apply. It seems unnecessary to be honest when I'm already indoors and not sweat so the sunscreen can't run.What about you? Do you re-apply your physical sunscreen every 2-3 hours when you are indoors and not sweating? Is it necessary?
Girls Blog 2015
Submitted by Redhaired103