This is so true... I never burned until I was in my mid-twenties no matter how much skin exposure or how long I was out in the sun... then things changed. In hindsight the change was due to a cumulative effect of poor diet and lifestyle. I could not stay out in the sun for more the 30 minutes at a time or I would burn, occasionally pealing afterwards. 2 - 3 times a week for 15 – 20 minutes early morning or late afternoon were needed for a while to develop a base tan to handle any more sun.
Last year about 2 - 3 months into my health journey, this was still true. This year I have had several times of 2 or more hours out in the midday sun without a shirt. My skin seems to bronze before my eyes.