I don't know what you're gonna do, but I can tell you what I would do:
1) I could prove who I am by my DNA.
2) Because of that, I would be a media sensation since I will be 40 years younger than I should be.
3) I could parlay #2 into significant amounts of whatever has replaced money, either by telling my story, or by peddling snake oil as a fountain of youth.
4) I would go hang with my daughter, who would be late in her career. I would meet my great, great grandkids, which few get to do.
5) I would reap the benefits of whatever Medical Science has learned in the previous 40 years which should boost my life expectancy dramatically above my peers (the 40 year advantage notwithstanding).