I think if we're honest, we all want to change the world, or at least our corner of the world. We want to make a difference to someone, anyone, proving that our existence isn't in vain. To show the glory of our Lord, the One to whom we've pledged our lives.
Sometimes we don't think that all the little things we do during the day add up to much in the big scheme of things. I've come to believe this to be wrong. We may not have the best job or the best family life etc. etc. But we have a HUGE Savior. And the attitude in which we work, play and serve is all-important. There are a lot of things we can't change. Period. However, one thing we can change is our attitude. Find joy in the small things. Give praise to the One who gave you life, no matter what your activity is. Someone is watching and is formulating their view of God and Christians by your life.
So determine to be a good example. You'll be an example, good or bad. Lead the way to the ultimate Love and Power of the universe. Be thankful for your life and use it the best you can. This is your purpose. Know that it brings a smile to your Father's face.