Each of us is given many talents and gifts. I believe it is important for us to know our gifts, use them and cultivate them. There are two purposes for doing it.
The first reason to know, use and cultivate your gifts is that it will enrich your life. We all have purpose filled lives. I am not talking about one specific path or purpose that you must fulfill. I am suggesting there are in fact many purposes to each of our lives. Sometimes one moment in time with a stranger could be life altering, for them or for us. That would be an example of an important purpose in life being fulfilled. Helping ourselves would be reason one.
The second reason, and make no mistake about it change begins within, we all seek an enriched and fulfilled life for ourselves so  we can fully contribute to fulfilling and enriched lives for others. So helping others would be reason two.
In my experience, whenever I help another I also receive. It is included in my giving that I am always a receiver. This is not to say that one should seek personal reasons for helping or giving prior to the undertaking. I am simply commenting that there will always be a gift for us in everything we do and we should consciously look for it and accept it with an open heart. When we are giving we create an energy of exchange. If we ourselves cannot receive we change the energy to whom we are giving as well.
Sometimes, in my past anyway, it has been difficult for me to receive. I was great at giving but not at receiving. And then I came to a conscious awareness that I was actually receiving and rejecting. It dawned on me that it was not kind to reject gifts of giving, from others nor from myself, and so I consciously started to not just accept but actually celebrate all that I was being given.
Now I live in a perpetual state of sharing. Now I understand that giving and receiving are part of the same energy and without the one the other cannot exist. So, I would suggest to you that the answer to what makes your contribution important lies in the conscious awareness of what you are giving and receiving on a regular basis in your life. Let yourself know the answer. Accept more love, kindness, positive energy, material wealth into your life and share whenever and however it occurs to you to do so and then the answer to the question will be easy and known to you. Remember what I know about you. Your contribution is important.
For my own part, it has been both interesting and enlightening for me to write about this subject. I hope that you receive as much reward from reading it and undertake whatever self-exploration as desired. I shall do the same over whatever amount of time it takes me to more fully understand my answers.
