I think a lot of people (myself included) struggle to notice happiness! We notice being sad because it's unpleasant, but we 'forget' to notice when we aren't sad because there are so many things that distract us every day! I try to practice enjoying little things, like the taste of my morning (and afternoon, and evening!) coffee, or a good meal and not to just drink or eat them quickly and move on to the next task. So for me happiness is taking a few extra seconds (only a few) for everything, just to acknowledge how it makes you feel and let yourself enjoy it. So when the birds are singing, listen for a moment, when the sun is shining stop to feel it, looking up at the stars on a clear night and noticing how big and beautiful the world is and how small our part of it is! It might not be 'I won the lottery' happiness, but that's everyday happiness to me!