True happiness

1) Being around:
     Babies/ toddlers
     Very old people

2) Doing simple but good things to/ for people and random strangers:
     Smiling and greeting a passerby.
     Holding a door open for the person  behind you.
     Saying "Thank you" and "Sorry".
     Pitching in for an over burdened colleague or friend on your own.
     Bringing coffee or snacks for the colleague having a rough day.
     Talking nicely to a roadside beggar or a eunuch on the street. Remember they are not spoken well with (in many countries), which explains their natural distrust towards strangers.

3) Nurturing:
     An indoor plant.
     A hobby

Ps: I shall happily embrace just additions to the above list :)