There are, at times, people who are so exuberant and expressive in worship that it causes others to ask;

"Why do they do that?"
"Why are they so loud?"
"Why do they clap and shout like that?"
"Why can't they chill out?"

I used to answer those questions by saying that it had to do with their personality or maybe even their culture, but I don't believe that as much anymore.
Now I believe that it is their testimony that causes them to worship like that.

I've found that often the people with the most over-the-top expressions of praise have some pretty incredible testimonies and if we just took time to listen to their stories it would make perfect sense to us why they sing and dance and shout and clap the way that they do.

Like the guy that survived being shot 9 times, who claps excessively loud during worship.
Or the woman that's finally free from a drug addiction, who shouts out loud while she sings.
Or the person that spent the better part of a decade in prison that really knows what it means to be free in Jesus.
Or the young lady that was sexually assaulted but knows that Jesus has come to make her whole again.
Or the family that was broken but is now restored.

Don't judge other people's worship. If you want to know why they do what they do, ask them their story. I think that most likely, once you've heard their testimony of God's goodness you will find that their worship is not excessive, but appropriate and more proportionate to what God has done in their lives.

IN FACT, it might even cause you to do some soul-searching regarding the praise that you give God in private and in public.