There are two possibilities.
In life, you may follow circumstances – making your peace of mind depend on them, or you may follow your peace of mind – without worrying too much about the circumstances.
In the first case we are doomed to experience constant ups and downs – for it's impossible to control everything and everyone. We also don't really have chance to take a closer look at what we really want.
In the second case we make decisions oriented on the state of mind – and not on shaping the circumstances at all costs. We also have a greater chance to be at peace with ourselves.
In other words: we may battle reality, try to control it, assuming that specific conditions determine our satisfaction, or we can – caring for ourselves and doing whatever supports us – maintain a peaceful state of mind and remain unaffected by changing circumstances.
That's in a nutshell... :)
With INTŮ you will get to know the second approach.