Iron sharpens Iron, so a friend sharpens a friend. Proverbs 27:17
There is an iron file that is used to sharpen steel (which contains iron) blades. I just remembered something from my childhood. My sister would take the blade off the lawnmower and sharpen it with a file. The interesting part was watching all the shavings fall off the rough edges that had no purpose. The dullness that need to be sharpened. She had to be careful in picking up the shavings because when you cut yourself with something dull it causes more damage than if it were sharp.
When we encourage one other I have learned that it often comes with constructive criticism given out of love. It is not always easy to smooth out those rough edges is it, but with the help from our friends they will help us see what we should be shaving off. There are times we become dull in our faith when the trials of hit us out of nowhere. Thank your friends for taking the time to keep you sharp and supporting you through thick and thin. We should always take the time to edify - instruct or help improve someone the mind of knowledge; to teach or persuade. It is comforting in knowing our friends take the time to build us up and vice versa.
Building one another up includes pushing each other to reach their full potential. When we see what our friends are capable of we should encourage them to take the next step. Walking through life with your friends and encouraging them to always do a little better then seeing them achieve their goals and dreams is a blessing that you are a part of. Watching each other grow spiritually is amazing especially when you know where they came from.
I could write about so many other ways we can build each other up, but I will leave that to you to think about all the ways you help sharpen your friends. So encourage each other and build each other up, just as you are already doing. 1 Thessalonians 5:11