I generally do 25, a 90 second plank, then another 25, then 25 dumbell curls on each arm with 15kg and 100 sit ups. The push ups I do slow though to make them harder. I’ll give 100 a go later.
*edit* 50 straight is no problem and if you keep it up every night, 100 should be easily achievable in 6 weeks. I’d like to see people doing them with straight backs though – makes me laugh when you see folk doing them and they look like they are trying to do the caterpillar 😉