Do 50 sit-ups and 20 push ups everyday for one month

I have been quite the lazy mofo, setting foot in a gym to exercise a whooping 3 times in past 6 months. I embarked upon this goal to help tighten up my abs, tone up my arms and inject some self-discipline into my life through daily repetition of the same task. While I can do 50 sit-ups in my sleep, doing them daily has noticeably tightened my stomach. I have pitiful upper body strength, and have an irrational fear of ending up like this:

if I engage in more than minimal strengthening exercises, but, I figured 20 push ups probably wouldn't get me there. It was a sad struggle at first, but then became almost easier than doing the sit-ups. My arms feel stronger and look a little less wobbly. I plan to try and maintain these exercises on at least a tri-weekly basis, as they really only take less than 2 minutes before I hop into bed. Next stop, getting into some semblance of an exercise routine!