In case we didn't get it from reading the last 25 Psalms, David has a pretty big ego. He won't sit with the vain, liars, evil-doers, wicked people, sinners, murderers or people who give bribes. Fun people, in other words. Why is he so awesome? So he can praise god, of course!
David wants attention again, but god ain't answering.
David thanks god for his victories in war and smiting his enemies and bad people and stuff. 122 of these to go.
David describes the voice of god: it's very loud, it carries over water, it's powerful and majestic. It can break cedar trees and make them skip like baby unicorns, it can split fire, cause earthquakes and make deer go into labour.
David thanks god for giving him victory and not letting him die. He informs us that god's anger lasts but a moment, which is a pretty liberal definition of 'moment' if you remember Numbers. He's happy now and has cast off his sackcloth for his dancing clothes.