Should one adapt him/herself to the environment and situation, or adapt the environment/situation to his/her needs? Which one of those is "the key to a better life"?

Oftentimes it is impossible to adapt your situation, so I think learning the talent of stoicism is extremely valuable. Once you learn those coping skills you can use them on any hardship that ever arises.

That’s not to say one should just sit back and accept wrongdoing in the world. Where there is power to change the situation, that power should be exercised.

Both. Make the best of the situation. Sometimes you can’t change your immediate environment. You can only work within its parameters to make it as pleasant and tolerable as possible. That may involve changing your self, and your expectations, to some degree.

God, grant me the serenity to accept the things I cannot change,: Courage to change the things I can,: And wisdom to know the difference. – Reinhold Niebuhr

^^^ I thought Billy Jack said it.

I had to look it up.

Oh, I believe you. I was only half joking. The first time I head it was in the 1971 movie Billy Jack.. The whole movie really made an impression on me, and especially that prayer. Of course, I was just a kid, so the Serenity Prayer will be forever mixed up with that movie.

Better luck altering the individual to the environment than to expect the environment to change for the individual.

I would prefer coexistence with the environment, over bending the environment to our will. But it doesn’t matter what I think…

I see no reason to adopt one philosophy over the other. Whatever works, keep it loose. Each circumstance requires an independent assessment. I spent three months in a rancid, crowded, brutal Venuzelan prison. The environment wasn’t going to change, but I had to adapt quickly or die. You can make a dark, gloomy apartment into a nice one, you can change to a nicer location. You can get a better job. You can make and keep peace in your house. You can both change your environment, or adapt, depending on the circumstance. I don’t find adhering to any one philosophy necessary to live happily and to do so might even lessen one’s chances of survival. Philosophies are the luxuries of academics.

It’s often impossible to change the world; someone once told me that life is what happens while we’re all busy making our plans. We can’t control how people choose to treat us; the weather never asks for our opinions; no matter how much we practice medical self-care and try to stay healthy, we can’t always avoid sickness or disease.

Given all that, I think we live with a combination of adapting and changing. If a bad situation’s tolerable and even somewhat reasonable, we might be able to modify and improve it, combined with managing our own reactions to what occurs. But, if circumstances are truly untenable – they damage us, and we can’t change them – it’s best to leave if possible.

Be like a river.

George Bernard Shaw wrote about this:

“The reasonable man adapts himself to suit his surroundings. The unreasonable man adapts his surroundings to suit himself. Therefore, all human progress depends upon unreasonable men.”

Adapt or die.

I agree with @Espiritus_Corvus and, I’d also add, examining your programming and identifying how many ” shoulds” and ” should nots” fuck with our realities. I have undergone being wiped out from the recession a few years back, losing it all. Work, home, savings, a beloved pet.
I have had to do some hard work in this area. Identifying and realizing there are no “shoulds” or “shouldn’ts.” I still can get stuck sometimes in a ” it shouldn’t be this way” mindset and it takes some doing to extract myself from this negative loop.

” I should be retiring and traveling and looking forward to my golden years.”
“I shouldn’t have to struggle financially like this at this stage of the life game.”
“It wasn’t supposed to be this way.”
On and on.

Well it is this way and I have and continue to adapt.
I have learned that I am far more creative, resourceful and adaptable than I ever knew.
There are a couple of sayings I repeat to myself when the dark days take over.
Our programming is pretty hardcore and untangling it is not easy.

” When you fight with reality, you suffer: Byron Katy I believe.
” Don’t should on yourself.” Anonymous
” Shift happens.” Unknown

The “key to a better life” is to understand that you are not separate from the environment or situation.

That requires breaking from the idea that you’re a little being, contained in your bag of skin, with your own agenda and preferences, struggling against a world “out there” that’s often at odds with how you want things to be.

In reality, all of this is densely interconnected, less a collection of beings than a vast explosion of being, with nothing separate or outside. Your self isn’t some little tiny part of this huge inter-being, but all of it. In fact, much of what is wrong with the world comes from the widespread failure to appreciate the truth of this.

To see things this way is to want all of us to be happy and at peace, and to work for that. The first step has to be to get at the root of our own sense of separation, that which makes us self-serving. There is a certain quality of equanimity that comes with this; circumstances just don’t bother you as much because they aren’t experienced as a personal insult.

When this is done, then it comes naturally to work for the peace and happiness of everyone. This can be on a material level, doing what’s necessary to alleviate hardship (which you now see is not “just their problem”). But what’s ultimately important is to help dispel the general sense of separation keeping people from being happy. This is a big undertaking, but it can begin simply by engaging with others not as others, but as ourselves.

So it’s not that you stop caring what happens around you. It’s that the center of your concern moves from how circumstances affect you to a generalized concern for the well-being of everyone. Strangely enough, there’s great peace and happiness in that.