So I have all my knowledge of martial arts, science, construction etc?
I mean seriously almost anyone with current day knowlege (who actually worked for a living etc, built things etc), would basically become a god.
First you take the tribe/town/city of people around you and show them how to improve their lives drastically, becoming their leader. You then train them, and upgrade weapons etc, start mining for materials that you need to eventually create a small nation that is far advanced compared to everyone else.
Then you just start dominating the world, expending constantly, upgrading technology while you let your minions do most of the work, teach knew young generations advanced education, math, constantly inventing knew (old to you) things etc.
Not only would you live to an old age, you would drastically change the history of the world.
In fact you could also set things up to ensure that the world never gets to the point it's at right now, ingrain population control at an early age (restricting the number of children per family to 3), prevent damaging of the earth and use natural sources of energy right from the start (even if that is just hydro and wind initially).
You could save the world!!
Well, that's not true of necessity. Like, do you know how to do stuff like make concrete or whatnot? Or how to do whatever else? Nevermind that you'd need to get the clout to have your words carry any weight. Some stuff might be realtively easy (like bathing) but if you think you're suddenly gonna get your little tribe outfitted with iSwords you're probably wrong.
There's also the fact that the minute you start talking about shit or showing off weird things you're gonna get stoned to death as a demon and a heretic