I've thought about this a lot over the years. A while back it occurred to me that there are two ways of doing this.
The first is the way most people think about it. Basically, you become immortal and live until the end of the universe and beyond. Maybe by becoming a robot or whatever.
The second way came to me while smoking ganga maybe a year or so ago. It happened when I was totally sideways and in a "time warp". This is when you believe maybe a few hours have passed but it's only been maybe a half hour or so.
This really became real once I discovered DMT. Sometimes time has no meaning when I'm there. And I realized that the difference between living a very long life and a very short life could simply be ones perception of time. Could an ant feel like it's lived a thousand years even though it dies after one summer?
Well, what if you could feel like time slowed down so much that a second felt like a year. What if nothing changed except for your perception of time? You couldn't think faster, move faster, or do anything faster (or slower) but just your perception was changed... Well, maybe you could feel like you've lived for forever.
Oh my god. I broke it. I broke reality.