The first month is one of the most difficult months. The body takes some time to adapt to all the new physical exercises you are doing. I tried to do a little bit every day. For example, It does take time to build up to the amount of pushups and sit ups needed to be done to complete the challenge. I started with 40 and increased a little more each week until I reached the amount that was enough to complete the challenge. Look are your numbers from the first month a feel that sense of accomplishment.
I know your sit up numbers are not correct. Maybe sensei can fix it.