Then i recommend you find a chin-up bar and try to do chin-ups.
Even if you can't do any, try to get in position and hold it there
as long as possible. Hang in there. In time to come, you'll be
doing chin-ups like no tomorrow.
You have to be damn regular about doing those crunches. The 1st
time you start with a lot, you'll feel the pain there for a few
days. But don't the pain be a turn off. Carry on even with the
pain. No pain no gain. In reality, it takes only 7hours of good
sleep for the body to recover exercise strain. You skip even for a
few days and you jolly forget about the routine, coz you would be
feeling too turned off to even continue. 
