Tell everyone what makes you smile, what makes you happy, what makes you laugh.
It makes me smile and makes me happy when people that I come into contact with whilst going about my daily routine are genuinely courteous, helpful or just happy themselves.
For example, when I go the shop on a morning to get my dinner for work, and the person behind the counter is in a cheery mood, and really helpful, it sets me off in a good mood for the day. Same goes for happy bus drivers (as rare as they are)