I did 1000 situps, 1000 push ups, and 1000 squats every night for 3 weeks straight…it pretty much took over my life. At the very best, I could knock out the push ups and squats in around 50 minutes by doing 20 of each on the minute every minute. The sit-ups, on the other hand, took FOREVER. The most I ever did continuously was 505 and that took 30 minutes nonstop. These exercises usually ended up taking hours upon hours because I broke it down into smaller chunks.