The way we live our life determines what kind of meditation we have, and the meditation we have determines what kind of life we live.

There is a very strong link between our breath and state of mind. Lust, fear, excitement all cause us to breathe very fast. Pranayama helps us slow down our breath which immediately silences the mind. 

It doesn't last, it's just step one. It's the perfect tool to induce knowledge. We can turn the mind inwards immediately.