In our instant-gratification society, I am concerned that young people do not understand that consistently making decisions geared toward long-term happiness does not preclude them from being happy in the short term as well. What it does mean is that if they constantly opt for instant gratification without regard to the long-term consequences of their actions, a lifetime of regret awaits them.
Life should not be all pain and no play, especially for young people. The formula is simple: Encourage children to make far more long-term-happiness decisions than instant-gratification decisions if long-term happiness is their goal. Then make sure they understand what the result will be if they do the opposite.