Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne.
Think that you are part of a big construction called science and you are not just a chemist but you are scientist. Be modest but proud. Modest because you know you will not be able to solve other problems because your life is too short. But be proud because you are contributing to it. Some people will bring a small stone to the building and some people will bring a big one but nevertheless no one can take that stone away from you.