Helping Others Helps You: Philanthropic and charity activities help increase your self-esteem. Jot down your thoughts and feelings before and after the activity. You can volunteer at the local shelter or old age home. Participate in a charity marathon (it's a great way to stay fit and do something good). Even throwing a garage sale and donating the profits can change the way you look at yourself.
Write a Gratitude Letter: Thanking someone is a positive feeling for the recipient and you. Express yourself truthfully and why you are grateful in clear terms. Deliver it personally, watch how the recipient accepts it and witness his/hers reaction. If letter-writing is not your style, give the person a small but impromptu gift, something that will make them happy and bring a smile to their face. Giving someone a flower or a bar of chocolate or picking up a loved one from work or even complimenting someone are all simple yet giving gestures.
Love and Listen More: Maintain your relationships with your loved ones. Communicate more and listen to your partner. Whether good or bad news, be attentive and constructive. Demonstrate your love more often (be more physically affectionate). Don't assume things are understood or a given, it's nice to hear sentiment once in a while. Forgive and forget issues and conflicts, it will make you feel good inside.
Read more at Buzzle: http://www.buzzle.com/articles/positive-psychology-exercises.html