Oh yes, if there is something that helps in the quest for happiness and contentment, it must be appreciation !
" appreciation: esteem, estimation, valuation, value assessment "
As you can deduce from the description and from interaction with others, this is a concept that works both ways. That is also the beauty of it.
Not only is it agreeable to feel yourself appreciated for who you are or what you do (makes you wanting to stay with your partner or employer), it's even nicer to be overwhelmed by the image of something beautiful, to feel the glow of something warm, to capture the intelligence of something clever, to laugh at a good joke,.. all sensations that enlighten your soul and embellish your life.
If one can generate appreciation from the inside and show this to the world, one is a happy person, I think