OK...you look at your manual, and it says 1/2" - 3/4" of slop at the mid point on your swingarm. So you set it up...and it seems too tight.

So, here you go:
The next time you pull the shock to grease all your linkages, keep the rear tire and chain on the bike. You want to position the swingarm STRAGHT OUT from the frame. Feel how taught the chain is. There MUST be some slop in it! Not much, but THERE HAS TO BE SLOP. IF there is ANY tension, this will bend the teeth, and heaven forbid, destroy your hub.
Keeep adjusting your axle until you have looseness at max tension on your chain. This IS where you want your chain.
Re-install your shock, after a VERY THOROUGH greasing of your linkage, AND lubing your chain.
With your bike on it's stand, pick a VERY CONVENIENT place to pull up your chain up and measure the distance between the chain and swingarm.
Tatoo this number to your little brothers forehead (I'd say girlfriend...but it might not be her forehead...even if she agress.). Rotate the tire and check this gap in several places >> chains have tight spots and loose spots.