What Makes a Good Friend?

That is the question that has been on my conscience today? I'm beginning to wonder if I am a good friend. Last night I got a text from a friend basically saying goodbye to me because I guess I wasn't paying him enough attention. I can't say that I was shocked. I already felt as if I was blowing him off time and again because other things came up. What is fact is that I am busy, and sometimes things get lost in the hustle and bustle of my life. Not that that is the greatest excuse in the world but I was trying. I often wonder about the amount of effort I put into my friendship relationships. Do I try hard enough? I'm not the most social or outgoing person and 9 times out of 10 if given the option to go out or stay in I'll stay in. The thing is that I cherish my friendships and people who are my friends mean a lot to me. Even if I don't reach out it doesn't mean that I'm not thinking about them or praying for them. I'm just, I don't know, not the type to call people on the phone (text is more my style), I'm not a spontaneous hanger outer, not the type that this world says makes a good friend. What people don't understand about me is that I can be just as content by myself as if I was out with friends. Nevertheless, I wish that I was a better friend and at this point I'm just frustrated because I can't figure out how to be that without totally destroying my comfort zone. Being constantly on edge doesn't a good friend make either. What is the happy medium? How do I make time for my relationships when I'm pulled in all directions and every thing and one wants my attention? What would make me a good friend?