In honor of it being Friday, I'm going to keep my thoughts on boasting boiled down into 4 points. Because, let's face it, nobody wants to read on a Friday!
1) Boasting and envy are closely linked to each other. Most of the statements in this passage are linked in pairs. This is a great example of that. Boasting about yourself or your accomplishments causes others to envy you. When we envy somebody, we will find reasons to boast for anything to make up for our perceived shortcomings. When we envy, we're saying "I'm not as good as you. When we boast, we're saying "I'm better than you."
2) We boast for attention, but most times we just annoy everyone around us. We've all been around that person that always wants to talk about themselves and the things they've done. Let's face it; often times we are that person. All it does is cause us to appear very self-centered and inward focused. There are better ways to receive attention than by just talking about our own accomplishments. Try creating meaningful conversations instead :)
3) Boasting attempts to take the glory off of God and put it on us. It becomes hard to share the Gospel of Jesus and the mighty power and wonder of God when we attribute things He has done to ourselves as if we were the only ones that mattered. God has given us more than we could ever possibly deserve, and serving God is an amazing blessing. Sharing what God is doing is a powerful witness tool; stop inhibiting God's work by trying to promote your own self-image.
4) Instead of boasting, use your energy to lift up others with encouragement and recognition. This allows us to move from self-centeredness to others-centeredness. When you let someone know that you've witnessed the things that God has done through them, you are providing them affirmation that builds closer relationships and you encourage them in their own walk with God. And when you let someone speak those words into your own life, you in turn will be encouraged to continue seeking God's will and lead others in that direction.