Stipulations:
- You cannot die and are immune to disease
- You cannot alter the future such that you change the world from your point of origin. i.e. You cannot become so famous that future people recognize you as immortal.
- If you vary the timeline too much you will cease to exist.
I would have said start betting like Biff Tannen, but that probably will end up changing the timeline “too much”.
But if I can’t die and am immune to disease, I guess I exploit that. Can’t drown so I’ll hop in an ocean and go somewhere. No need for food or lodging. I’ll just wander for the next 100 years and peoplewatch.