My grandma has skin cancer, which has contributed to my caution about sun exposure. Vanity plays a part, too.
I have a couple mostly full tubes of sun block (plus two tubes of face moisturizer with SPF15), but given the time I spend outside walking dogs, gardening, and doing other things, I could easily use them up quickly. Not to mention that it can be a pain to remember to reapply as I sweat.
I wear a light -colored, washable brimmed hat frequently in summer, which reduces my needs for sunblock on my face and neck. Today, I gardened in a light-coloured, long-sleeved cotton flannel shirt, which was actually fairly comfortable. In combination with my gardening gloves, I felt well-protected.
I looked up the sun protection that different types of clothing provides to confirm whether it was reasonable to believe cotton flannel has a high SPF. The fabrics that are typically higher are synthetics, which would be horrible to wear in the heat, but cotton flannel is tightly woven, so it seems like a good choice.