Friends forever?

I do not take friendship lightly; I believe true friends are a blessing.  I have known one of my dearest friends since we were three.  She turned 40 last week, and I wished I lived close enough to celebrate with her.  We have a friendship that no matter how much time elapses between visits, it is as if only minutes have passed.  Don't you love having friends like that?
I have another friend from high school that I talk to a few times each year.  We had our differences sometimes in high school (all probably my fault), but when we went off to separate colleges, we stayed in touch, and spent quite a bit of time together with our hubbies as young married couples.  She is ALWAYS positive, and any time spent with her is encouraging to me.
I have another friend I worked with over the summers during my college years. We were acquaintances then, but ended up at the same church in our late 20's.  A few years later, our church began "40 Days of Purpose" and we had a small group in our home.  She and her husband came, and now, they are some of our closest friends.
I have a friend who is ten years younger than me, but oh, so much wiser than I am.  We met while we  lived in Florida.  Both families have since moved to different states, but we typically talk at least once every two weeks, even if it is a text requesting prayer.  Her husband is interviewing for a job near our home (within 1.5 hours driving distance), and I am hoping and praying it works out because I miss spending time with her and her sweet family.
I have other precious friends, but none as close as these.  I am a bit of introvert, and I don't actively seek out friendships.  If I feel something "click" with another person, I will exert more effort, but if I sense only superficial connection, I am friendly but less vulnerable.
Since we moved to this area a couple of years ago, I have met many wonderful people through our church, the kids' schools, sports teams, etc.  I would consider many of them "friends", but not necessarily close ones.  I have met a few women who I seem to have much in common with, though, and I am thankful for that.  I am waiting to see how God blesses each of those friendships.  My mom always said, "If you want to have friends, you have to be a friend", so I have tried to open myself up to share life with them.  I believe He places everyone in our lives for a reason, and I want to learn through the experience, whether the friendships develop into lifelong ones or not.
How about you?  Is developing new friendships easy for you?