Post humanism is, essentially, what it will be like to be "more than human" — ie, what are we going to evolve to next. This could be purely biological, purely mechanical, some kind of nano-tech, or a combination of the lot.
Transhumanism is more or less synonomous with "human enhancement". This is the stepping stone to post humanism.
Of course, many people see this as complete nonsense — and that's totally fine.
However, assuming people think "Hey, become better? What a great idea!", there are two main approaches:
1. Wait Till Technology Does It For You
I know a guy who's a great example of this. He's 29 (but looks 49), chain smokes, does a lot of drugs, and so on. He plays guitar, but his body is so massively crippled that he can't play it for more than 5 minutes at a time without extreme pain. He can't do any exercise because every joint in his body hurts. This isn't a genetic disease — bad life choices have gradually crippled him.
He's firmly convinced he will live forever.
I suggested that perhaps he should cut back on the smoking, but he disagreed. Why? Because he's sure that 'science' will catch up soon enough that it'll be able to fix all his smoking related issues — oh, and all his other health problems as well.
Ahh, well. Ok then.
2. Start Now
Aubrey De Grey is a main figure in the immortality movement. He's opinionated as hell, so unsurprisingly, his ideas are hotly debated. He does however have some interesting points.
One of his key tenets is that if you can live another 30 years, then medical technology will improve enough to allow you to live another 30 (in robust health — we're talking quality of life here too, not just quantity). In the 30 after that, technology will improve to allow another 30 — and so on ad infinitum. A longevity equivalent of Zeno's dichotomy paradox.
The critical first step is that you want to hit that +30 year mark in as good a shape as possible. It's touch & go which aspects of human frailty will be dealt with first — so if, say, you have destroyed your lungs but the rest of you is fine, you might die anyway if medical science hasn't quite figured out lung replacement (or lung cancer) yet.
Now, health & wellbeing is a many faceted thing. Is it worth having a healthy body if your mind has completely deteriorated (or vice versa)? All the different aspects of your system have to be kept above a certain baseline, otherwise the entire system will collapse in on itself. Witness how quickly old folks can spiral downhill if they lose their mobility, catch pneumonia, or lose a loved one.
So, unsurprisingly, this is the approach I prefer. Working on improving my physical, mental, emotional & spiritual wellbeing, more or less all at once — thus ensuring maximum longevity (more importantly quality of life, not just quantity), and, eventually immortality.
The really interesting thing is — once you start looking at some of the technologies that have become available to assist & improve in these areas (and boy, the internet is a godsend for this kind of research), you quickly become exposed to more & more ways to improve your life. Not only that, but many of these technologies are both exponential in benefit & complementary to each other. You start using even a couple of them, and massive chunks of your life radically improve at once. The more you use them, the faster & more significantly your life improves. Even better than that, many of them are both free and stupidly simple to implement.
Of course, which technologies (or indeed any) to use is always a personal choice — and different things do just seem to work better for different people.
An unexpected benefit too is — once you start looking at some of these diverse aspects of the human system, you'll start to see that it is possible to live a life with higher highs (& much higher, or even non existent lows) than you might ever have previously dreamt possible.
Happier. Fitter. More energy. More peacful. More fulfilled. Wealthier.
I look at all this, and to me at least it seems obvious — why wait for the future to arrive when it's becoming easier & easier to race up to meet it, with a giant smile on your face?
But of course, as usual, there is always choice 1.