If life is so short, why do we do so many things we don’t like and like so many things we don’t do?

Imagine, You have a ruler, you can see the point where it starts and where its ends, you see the length of it, but when you just see part of it and the other part is under pile of papers, you will put many possibilities for how tall or short the ruler is and you will lean more to the one possibility that will benefit you or the one you really want to have.  I meant from my example, we know when we started our lives but our ends still under pile of unknown. Yes life is short but depends on whom, we experience people dying, and some people have short lives than others, but as the selfish nature of a human being that most people have which is the inner believe that we are different and we are immune to bad things to happen to us or death. Though, from time to time fear will haunt us but life’s temptations will make us get distracted. For that we sometimes act like we still have many other chances to do what we really like or don't like. The other reasons why we do so many things we don’t like and like so many things we don’t do? Fear from failing, or even fear from trying and doing what we really want. Sometimes we stick with the things we use to, they are safer. In addition, doing new things is always scary. Also we always think we have the time to do what we want, but we always delay them. Also fear from what other people will think if we do what we want to do. Finally the most important reason is we are just human beings and that is the definition of the opposite form of god, we full of errors and mistakes, and we are not perfect. We sometimes choose our choices and then discover what we really want and what we like through the process of doing what we don’t like.