“A life is made up of a great number of small incidents and a small number of great ones.” – Going Solo by Roald Dahl. what does this mean?

Big, dramatic experiences don't happen often in life, for most people. Our lives are usually made up of many small experiences. They may not seem significant or worthy of newspaper headlines or even posting on Facebook, but little things can mean a lot. For example you might remember when someone was kind to you in some simple way. That is not an earth-shattering event, but it is meaningful. Similarly, we remember small hurts and may feel wounded for years over a tiny incident. I think the quote is suggesting that we should pay attention to the small moments of life and try to make the best of them.