There is something wrong with it. My 9-year-old (girl) can start my B&S mower 1st pull.
Does the flywheel brake (if fitted) fully disengage when you pull the lever on the handle? The engine should rotate with very little resistance when the starter rope is pulled.
If you are weaker that average for whatever reason, there are electric-start versions of many mowers - even budget ones, or you could fit a used electric-start engine to your mower. Not a difficult job if all the parts are to hand.
phil_saunders(a)bigfoot.com
Phil Saunders, September 2012