It seems to me that if we want to exemplify a life of grace and gratitude we need to do three things.

First we must ask God to help us to see ourselves more clearly. How can I be an encouraging person if I am always complaining about minor setbacks? Paul actually tells us to be thankful in all circumstances (1 Thessalonians 5:15-18).
So the first thing for me to do is to examine my own heart. Am I a grumbler or a critic? If so, I need to confess that sin and ask God to transform my attitude into something better.
Second, we must take action to encourage others, especially those who are going through difficult times. 2 Corinthians 1:4 tells us to comfort those who are suffering. We should look for ways to lift others up.
The first step is righting our attitude and the second step is taking action. So what is the third step? It's about establishing an appropriate atmosphere.
A follower of Jesus Christ should so desire to be an encouraging person, that she or he should set the stage for encouragement to appear. There are many ways to do this, but for this post I want to share one simple technique that you might want to try this week.
The next time you see someone you know, instead of throwing out that tired, old phrase, "How are you?," do the following. Ask them, "What's been encouraging to you lately?" This statement not only shatters the facade of "How are you?" greetings, it also signals that you are interested in establishing a deeper interaction. Moreover, it starts the conversation off in a place of positive reflection--what good has been going on in your life?
In summary, if you want to be a more positive and encouraging person, do three things. 1) Cultivate a life of personal gratitude. 2) Support and comfort others. 3) Begin your conversations with a focus on encouragement.
One final thought. Before you ask the question, "What's been encouraging to you lately," be sure to give this some thought yourself. Asking this question of others is not some kind of Jedi mind trick or networking gimmick. It's a reflective technique designed to help all of us remember the blessings we so often take for granted. And if you don't have an answer for this question yourself, it's going to be pretty embarrassing and uninspiring when the person turns the question back to you and you have nothing to offer.
What a great twist on a greeting question! Just thinking about my answer to it feels encouraging.