Go ahead and boast, God tells us.
Just boast in the right things.
We Believers are good at gushing about some great fellowship or church we belong to. There's nothing wrong with this, but if it doesn't get you to mentioning Jesus to the ones you are talking to they might just not get what you are inferring in a roundabout (and way too roundabout) way.
Boast in God. Tell people what He's done for you. Tell people how great He is. Tell people how He is the Constant in your life; how He is the Peace that truly "surpasses understanding." Tell people the blessings He has brought in your life. Tell people what you've been part of while you've watched Him work.
Tell about Him. Oh, mention Him. His name is Powerful! The name of Jesus stops people short. Why else would people who don't know Jesus use His name as a cuss word? They sense in the power in it. I don't like to hear people use His name wrongly but when I do I think it somehow in a weird way proves His power. I'm not advocating that at all. Please don't use His name that way.
But I wonder -- if you hear someone use Jesus' name in vain, what if you asked him why he used Jesus' name that way rather than some other word.....it could be a very interesting conversation.