Happy and contented are similar but different imo.
Happy is (imo) when nothing could be better and you are feeling great.
Contented is (im) when you feel fine and are at peace with your situation, even though everything is not completely perfect.
Me, I am usually contented. I like / love my life, my work, my wife, my kids.
Yet I also feel a certain restlessness. I cannot just sit back and 'enjoy' what I have, I always feel the need to learn new things, find out more.
Restoring razors, learning computer languages, learning martial arts, and most recently, I have started learning Japanese. Until the day I die, I will probably always find new things to learn.