For sunbathing in particular, do what Australia does:

- large scale public health campaigns on dangers of skin cancer. With a catchy song and slogan ("slip, slop, slap... Slip on a shirt, slop on sunscreen, slap on a hat")

- schools make it compulsory for kids to have hats in summer

- regulate tanning salons, promote fake tans in preference to sunbeds

- doctors check people for skin cancers during regular checkups

And over just a few years, being very brown quickly gets associated with being reckless and unhealthy.

In other words, regulate and educate

It’s not about regulation it’s about intervention. It’s not that you’re not allowed to saw pieces of yourself off with a chainsaw, stranger of a choice as that may be. The idea is people in your life who care about you may want to intervene to stop you, as no matter how pleasurable you might find what you’re doing to be, it’s slowly killing you.

And that’s not even going into the science behind addiction where the whole “but you chose to do this” gets more and more dubious the deeper you go.