[afoot]

Have children. (and hope for plenty of grandchildren, great grandchildren etc)

1,000 years is time for a lot of generations to pass. Sure, your particular DNA might only make up some small amount of someone walking around in 1,000 years, but that is an action you can take in your lifetime that will be significant. Bonus points if you educate them well and give them the resources to be as successful as possible.

[LyndsySimon]

I agree, but I think DNA is irrelevant.

Imparting your values on the next generation is the most durable thing an individual can do. The way I see it, it's a multiplier. I can only do so much in one lifetime, but I can raise my children to value the same things as me, and thereby guide the impact that they and their children will have on the world.