In order to be a loving person, one needs to feel loved. The more one is surrounded by love and warmth, the more loving and warm he will become towards others.
If you can be loving towards others, you change not only that person but society because that person will pass it on and it will spread like wildfire.
The other side of the coin is that one's negative traits also spread. If he is cold and distant then the receptors of his icy attitude will treat others the same way.
If, for example, in our culture, it was accepted that every morning men went to shul and before and after davening hugs were going all around - the entire atmosphere of our culture would become one of more closeness and warmth. Then these men would go to work and with that feeling of being embraced, they will embrace the world. But we go to shul, at best wish others a perfunctory good morning and the feeling of distance is perpetuated.
The Arizal says that before davening one should take upon himself to love every person. It makes for a different davening and a different day. Can we say that we honestly LOVE every person in shul or at work? If we don't then we are missing out on a MITZVA MIN HATORAH!!