People tend to pick friends similar to themselves, says Susan Krauss Whitbourne, in the Psychology Today article, "Fifteen Reasons We Need Friends." Taking this idea into account, it's safe to say that friends play a large role in helping you get to know yourself better. Since friends are like-minded people, they can help you figure out what your goals are and encourage you to stay the right track while you're trying to reach them.

In the New York Times article titled, “What Are Friends For? A Longer Life,” Tara Parker-Pope explains that in times of trouble, many people turn to their friends for support over family members or support groups. Good friends can help you cope with traumatic life events, including serious illness, divorce, loss of a job or the death of a love one, say experts at MayoClinic.com. With long-lasting friendships, comes greater peace of mind, because you know that through thick and thin, your friends will be there for you.

Friends step in and tell you things that the average polite stranger wouldn't. Whitbourne says that since your friends know your ins and outs, they are able to spot things that you can't see (or that you choose to ignore), and they have no problem telling you the truth. Everyone needs a reality check now and then. According to the MayoClinic.com, friends can also point out unhealthy lifestyle habits and encourage you to avoid or change them.

In a study cited in the “Wall Street Journal” article, “Beyond Facebook: the Benefits of Deeper Friendships,” writer Sue Shellenbarger examined the health benefits associated with friendship. Having friends reduces bodily stress, which leads to reduced blood pressure, a lower heart rate and fewer stress hormones. Knowing that you have friends to rely on provides an alternative to the traditional fight-or-flight response to stress -- especially in women, notes the Cleveland Clinic Wellness article, “The Health Benefits of Friendship.”