He who walks with wise men will be wise, but the companion of fools will be destroyed.
Not only are we known by the company we keep, we tend to absorb the attitudes of those around us. By consciously choosing to associate and learn from people who have demonstrated wisdom, we will seek to apply their methods and ways of thinking. We will walk the walk of the wise.
But if we choose to spend all our time with those whose actions and thinking demonstrates foolishness, that way of thinking will rub off on us as well.