5'8 140lbs(mostly leg muscle i think) about 28-29inch waistrecently started working out, doing things simple for starting off, but i cant seem to do situps too well. I'm far from fat, and i can feel abs underneath what little fat i do have, but i can only seem to get like 2 sets of 25 situps. i put my feet under the couch but since its so high off the ground i also rest them on a few mats. doing this i tend to feel more of a strain in my crotch/legs than my stomach. any advice on how to get a sixpack?(sorry if double posted, computer troubles atm)