If I may allow myself, from experience, I have learned one thing, it is not the years that forge a friendship, but the friendship that will forge the years. And to be a good friend, or to have good friends, you have to have heart I think. But not only that, it all depends on your aura.
I think that our "aura" plays an important role in our sociability and the way people perceive us. Either we are a sunny person (smiling, pleasant, etc.) or a grey person (moody, always suspicious, etc.) who would define our personality? In other words, either we want to get to know you, or we avoid you. Honestly, for me, friendship is a chemistry that is sometimes illogical, we can't explain it, it's like love, it's immutable.