I'm very disciplined. I'm super fair, adopted into a tan family in the 70s in the South. Let me tell you about sunburns! My mother used to put parkay on me because she heard it would help prevent sunburn. At the beach. I have had so many blistering sunburns that I'm sure I'm a walking risk for skin cancer. I don't want to jinx it, but my derm visits have been good so far despite my history.
All that said, I wear facial sunscreen daily and have mostly since my early 20s when I realized I could use sunscreen (don't laugh! LOL). I also wear a hat if I will be outside for more than a few mins. I wear body sunscreen if I'm going to be outside for any length of time Spring-Fall. I do not wear it just to walk to the car/shopping/errands. I do not wear it in the winter. I do still get caught offguard, though. My scalp got burned a couple of weeks ago because I did haircuts for DH and DD on the back deck. Forgot to put on a hat! Oops!
I do run low on vitamin D, so I try to balance some sun exposure with protection.