TIP #13: Do something to improve another person day, constantly.

We forgot how far be nice can go. Open the door to a lady. Help her carry her bags. Bring breakfast once a month (even better once a week) to that homeless guy in the corner you turn to work everyday. Cut the front lawn of your neighbor just because you are doing yours. Pay the starbucks coffee to the person behind you (or pay only $2 or their coffee, trust me, you will make their day). I guarantee you, that if you do something good for someone, you will simply be a happier person.
i.e. If you don’t believe me, think how nice it is when the person ahead of you pay for your coffee in Starbucks. If this had never happen to you, do it, and see the smile of the person behind you.
i.e.2 One of my favorite things to do in the store is to ask old people if they need help. Most of the time they do, and most of the time, you make their day.