I am stealing from William B. Irvine's book here... There are 3 categories of things:
1. Those over which we have control.
2. Those over which we have no control.
3. Those over which we have partial but not complete control.
It is foolish and detrimental to spend any effort thinking or worrying about things over which we have no control. These things include:
* The past
* The present
First, learn to accept the past, and internalize that it is fixed and not able to be altered. Therefore it is not worth fretting over. Then embrace the present-- love every moment as it happens to you. You might as well, because once it's here you can't change it. This is my definition of mindfulness. In practice, this will look like you noticing what's around you and feeling grateful for all of it. Your breath, your fingers, the daylight, that you have food to eat... look at this machine that lets you connect to anywhere in the world in an instant! (you get the idea). There are many techniques to aid in this, among which is mindfulness meditation. Another is called "negative visualization", in which you imagine life without something, and ideally accept the hypothetical situation as still liveable, in order to better appreciate whatever amazing luxury you happen to have. A common example is imagining yourself without vision.
The point of all of this is so that you no longer need to commit any of your precious energy just trying to make yourself happy with your life in the present. All of that energy expenditure is a distraction (and our culture is geared top to bottom toward trying to make you spend your time, money, and energy this way!). To be blunt, needing something specific to be content is a personal weakness. Once you really, truly embrace your present circumstances, you can focus all your energy on what you do have control over, which is actually quite a lot.
You have control over:
* Your goals and plans
* Your actions
* Your reactions to circumstances and other people
So what I think you're missing is that people who are successful "suck it up" but they don't push through years of hating life, because they don't hate their life. They love their life, and then proceed to make it even better. To put more a Buddhist spin, there are 2 ways to feel content: One is to satisfy every desire you ever have. This will never happen, because no matter what you get, it will never be enough. The other way is to eliminate the desire itself... and then achieve some of those things anyway, at which point they're pure gravy. You could think of it as a charity in which you're giving to a stranger: your future self.
Tl;dr: Right now you hate life unless you achieve X, Y and Z, at which point you'll feel satisfied (for a while). Instead, teach yourself to feel satisfied right now, and then throw yourself into whatever it is that you feel passionate about, as you are able.