We must be careful with whom we associate because we are continually exchanging magnetism with other people

 

We must be careful with whom we associate because we are continually exchanging magnetism with other people through our thoughts, through shaking hands, and through looking into the eyes of another person. As soon as we shake hands with someone, a magnet is formed. The person who is the stronger gives his vibration to the other person. We become like the people we mingle with, not through their conversation, but through the silent magnetic vibration that goes out from their bodies. When we come within the range of their magnetism, we become like them.

...

If a man wants to become an artist, he must associate with artists. If he wants to become a good businessman, he must associate with successful businessmen. If he wants to become a spiritual giant, he must associate with devotees of God.

How to be a Success by Paramhansa Yogananda