When we speak of a calm state of mind or peace of mind, we shouldn't confuse that with an insensitive state of apathy. Having a calm or peaceful state of mind doesn't mean being spaced out or completely empty. Peace of mind or a calm state of mind is rooted in affection and compassion and is sensitive and responsive to others.
If you want to change the world, first try to improve and bring about change within yourself. That will help change your family. From there it just gets bigger and bigger. Everything we do has some effect, some impact.
If you develop a pure and sincere motivation, if you are motivated by a wish to help on the basis of kindness, compassion, and respect, then you can carry on any kind of work, in any field, and function more effectively.
The future will be in the hands of those of you who belong to the 21st century. You have the opportunity and responsibility to build a better humanity. This means developing warm-heartednes s in this very life, here and now. So, do whatever work you do, but ask yourselves now and then, 'How can I contribute to human beings being happier and more peaceful?'
Ultimately, the reason why love and compassion bring the greatest happiness is simply that our nature cherishes them above all else. The need for love lies at the very foundation of human existence.