We are all travelers in the wilderness of this world, and the best we can find in our travels is an honest friend.
Courtesy costs nothing. Lower the toilet seat after use. Let the people in the elevator exit before you enter. Return shopping carts to their designated areas. When you borrow something, return it better shape (filled up, cleaned) than when you got it.
The happiest people are those who have discovered that happiness is a choice and not a result of circumstances.
In the realm of science, every question answered leads to new questions, driving the endless cycle of discovery.