We believe that relaxation is easy. To relax should be to do nothing, that is, the opposite to doing. Doing should be difficult and not doing should be easy. However, many people are actually very bad at relaxing.
The world is so stressed out and time conscious these days. Time is money. The goal of most people's lives is to achieve as much as possible in as little time as possible. Because of this achievement obsession relaxation has almost become tabu. Relaxing is still "cool" if covered by some fashionable title as "yoga" or "spa", but just sitting at home watching TV is not cool. We even look down on people who we think relax too much.
Just as with any skill, practise makes perfect. The more we practise relaxing, the better we get at it. People who are used to relaxing can get to deeper levels of relaxation (and the associated "deeper" brain patterns) than a person who never takes the time to breathe out.
Relaxation is important for health and caring about our health is important for self-esteem. We don't need to have a certain health level to have a high self-esteem, but we need to care about ourselves. It is perfectly possible for a person with poor health to have a higher self-esteem than a person with good health. What matters for the self-esteem is that you care about yourself and do whatever it takes to put yourself in as optimal physical condition as you can be in. Relaxing is an important part of taking care of yourself. This is one of the reasons to why relaxation and self-esteem are so closely linked.
The other link between relaxation and self-esteem is that when you relax you give yourself opportunity to tune in to yourself. When you relax you can listen to yourself and find out what it is that you really want and need. Again, by listening to yourself you show yourself that you care and this raises your self-esteem. Listening to yourself also develops your self-awareness. Self-awareness is the first important step towards self-esteem that you cannot skip over. Without self-awareness you cannot develop self-acceptance and without self-acceptance you cannot build self-esteem.