If only fitness was linear! I did X number of push-ups and ran Y number of miles on the treadmill this month. As a result I decreased my body fat by 2%, dropped 5 lbs, increased my push-up max by 4 reps, and dropped my resting heart rate by 3 BPM. Cool! Next month I'll do the same thing, drop another 2% body fat, lose another 5 lbs, etc, etc. Right? Wrong!
You may do the exact same regimen next month and get nothing to show for it —or, is it really nothing? One of my favorite personal training examples comes from a male client that I trained several years ago. This guy worked hard! He huffed and puffed, and lifted, and grunted, and from an exercise standpoint did about everything that I asked. One day he came to me sad and discouraged. For the last three months of hard effort he had no actual weight loss to show. Mind you, I say "hard" effort because this guy would drench two workout towels every workout! However, he decided to give training a break —he felt it just wasn't working for him.
Three months later I received a phone call from him. "I'm up 18 pounds", he said, rather discouraged. I used this opportunity to drive home the point that while he was training with me he might not have been necessarily losing weight, but was at least maintaining his weight, feeling good, and no doubt gaining some muscle! Persistence is key before just throwing in the towel.
Fitness, and especially weight loss, are not a perfect science! You can't predict the results based on any given training regimen. Put in the reps, eat the stuff you're supposed to eat (and avoid the stuff you're not), get to the gym on the days that you've planned, and just keep practicing the health and fitness lifestyle. Results will come — just never as instantly as we'd like! Remember, fitness is a journey, not a destination.