Before you speak, ask yourself, "Am I saying this to build this person up?" Often times, we speak reactively without thinking and sometimes we say things to purposely hurt someone else.
To build the habit of building others up, decide right now that you want good for others. Treat each person you come in contact with as if they are the most important person on earth and they are deserving of your attention. Be present with them. Be authentic with them knowing the only way you can be real and uplifting is to exist with an uplifting attitude.
Share that enthusiasm for life with others while being compassionate to their struggle, their pain or their loss.