anyone know how to play this on guitar?

I have what looks like a decent tab, but it has no rhythm markers on it, and I am very bad with rhythm and changes. Basically I have the rhythm down for the Gm7 chord but can't seem to figure out exactly where the changes are (I always seem to change a little late, and then stay too long in the next set of chords), plus I can't quite hear the strumming pattern for the Cm(ish) chords.

any help would be appreciated

edit: Doobie Brothers, just in case