Most songs are really not difficult to play. There are thousands upon thousands that just use 3 or 4 chords. It is what you do with them that can make them difficult.
The secret is to keep the strumming very simple. Concentrate on changing chords accurately, staying in time, varying the volume a bit. Many people fall into the trap of trying to copy the way others play a song and often try to tackle something that is too difficult for them.