Life without death and happiness without misery are contradiction and neither can be found alone, because each of them is a different manifestation of the same thing.
If you have peace of mind, when you meet with problems and difficulties they won’t disturb your inner peace. You’ll be able to employ your human intelligence more effectively. But, if your mental state is disturbed, full of emotion, it is very difficult to cope with problems, because the mind that is full of emotion is biased, unable to see reality. So whatever you do will be unrealistic and naturally fail.