If you have the power to order a specific function to your body, what would it be?

I’d choose that face you pull when a huge sneeze builds to a crescendo only to dissipate on the cusp of explosion.

Regeneration.
I give my body the ability to immediately regenerate any part that is removed, at will.

I’d sell a few organs to the highest bidder (outside the US) until I was wealthy, and then I’d start on a regular program of organ and tissue donation that would keep my body young and healthy as long as possible, while helping other people.

I’ll have what @ibstubro‘s having. And I know what I’m regenerating first!

And you can’t generate middle aged cells, @LuckyGuy, so you’d be like a teen again. That was part of my thinking.

Can I do a sort of “I wish for more wishes” trick, and order that my body “adapts to whatever new request I make”? (So then I can grow/regenerate/modify/undo anything at will.)

I would like to have a thicker skin, so that things that impact my life would have less effect on me.

Nothing. I’m good.

To retain hair and it’s color.

Fwiw I would like cholaraphill (or plant cells) in my body so I could feed on sunlight and heal amputations.

Or mitachlorians for Jedi powers

Regeneration, too I think. My back and neck hurt.

Order my body to regrow its colon and do it right this time. I don’t need an advantage over anyone else but being back on a level playing field would be so nice.