I'm willing to build up a pain tolerance until I reach​​ Pain Suppression

Immortality. Nice and simple

Sometimes being able to get harmed have it's on benefits. Like selling organs or donating blood. And other stuff as well

Invulnerability.

Immortality can be achieved by other fantasy forces.

Alchemy , magic, blessing,curse.

Immortality. If I could have an extra power to go with it. It would be Hypercognition.

The last one looks interesting