Re: I can't do a sit-up help?
There are many different ways to work your abs and core area. Yo can completely skip sit ups and still get a toned stomach area.
Learn to do planks they will really strengthen your core and from there you an add variations. If you feel you must do a sit up or crunch have someone show you proper form. You should NOT be feeling it in your back at all. You have to contract your ab muscles to propel you up. They may not be strong enough to do that, or your technique is way off.