Happiness, The feelings of your self satisfaction is depend on how you think. A small thing can make you satisfied, if you belief it's enough for you. On the other side a big achievement sometimes doesn't make you happy if you have a large number of expectation.
Self-satisfaction of monkey
Monkey photography
Think about the environment beside you. There are too many peoples who lives a very normal life compare to you. They can't cover their basic necessity. So at that point you are happier than them.
Be happy with what you have.
Do more work and expect a less. If you get something better than your expectation, that will always make you happy.