Understanding life has a lot to do with understanding its purpose. Why? Because we don't want to waste one of the most important resource time. Why time is important? Because it is finite. Well I can take more whys in comments if any body is interested.
When we apply for graduate schools or any academic jobs or highlevel jobs we are asked to describe, many times in written or a few times oral, of what our goal or purpose of applying for or working in that position is. This is because only then can they feel justified to invest in both their and our resources for society.
Most people search for their purpose when asked for. This is good and benefitial to society. But on an individual level if one wants to be really successful he needs to clearly understand the purpose of having a purpose in life and only then can he focus his energies effectively which is needed for success. But beware you cannot just describe anything that you want as purpose. You have to add wisdom and rationality for any desire to be called a purpose. This is possible only after considerable experience of the universe.
One essential phase in understanding the purpose of life is not having a purpose and feeling the need for it and honestly and courageously facing it to move forward to the phase of having a purpose. It's like building a bridge/building/subway system etc. We first don't have those, then we feel the necessity of those and then build them strong and effective and it takes lot of honest, courageous effort. The adjectives used for effort are non-scientific (but essential) and the effort would be scientific. The other phase is that it needs reevaluation, maintenance work too:) So the bottom line is just look around yourself in Nature and you will understand what are the phases.
Now what kind of purposes we can have. Based on history and current events we should have a purpose to live happily. For that we have to choose a proper method that will not get in others' purposes. After exploring for a while (for most people around 20-25 years of life - not kidding) choose a specific domain where you know you can contribute and work towards doing that. If that is not very satisfying then have a purpose to prosper because for that you have to do the above. It's just another way of looking at it - probably more common but not very insightful and nevertheless useful. Ofcourse:)