The purpose of meditation is to make our mind calm and peaceful. If our mind is peaceful, we will be free from worries and mental discomfort, and so we will experience true happiness. But if our mind is not peaceful, we will find it very difficult to be happy, even if we are living in the very best conditions.
When you buy a jacket, you pick the size to ensure it fits. Similarly, we live in a universe in which the amount of dark energy fits our biological make-up. If the amount of dark energy were substantially different from what we've measured, the environmental conditions would be inhospitable to our form of life.