There should be an O ring on the shocker shaft.
Dump all air in the shocker, and Before you sit on the bike, push the O ring up to the body, then gently sit on the bike, get off the bike, and measure the maximum movement and should be 38 mm.
Make certain that the rear wheel does not hit the rear rack if fitted.
Pump the shocker to your weight in lbs as PSI using a air shocker pump, with a screw on connection, so minimal air pressure is lost from the shocker, when removing the pump.
http://cruzbike.com/DOWNLOADS/KindShockPumpOperation.pdf
Before you sit on the bike, push the O ring up to the body, then gently sit on the bike, get off the bike, and measure movement.
This should be 20% of the max. movement, approx 7.6 mm.
If not, adjust the shocker pressure until it is.
Then go for a ride on your normal track, and check if the max movement is about 95%.
http://forums.mtbr.com/shocks-suspension/fox-rear-shock-pressure-132479.html