Happy, optimistic people give others the benefit of the doubt and expect to like other people (unless given a reason not to). Try adopting that mindset: when you meet someone new, choose to see that person as a potential friend whose company you might enjoy. Try this idea with your existing relationships too! Don’t assume a friend you haven’t seen in a while doesn’t care about you—instead, give that person the benefit of the doubt and assume that your friend’s absence has nothing to do with you.