I used to keep a food and workout log. I haven't for about 6 months. However, keeping a log was very helpful to me. I used it so that I would lift heavier or do one more rep than the previous week. I see people at the gym that go in on Mondays and do chest, I think 90% of us do chest on Monday, and lift the same weight they have been lifting for the last 3 months. Then they wonder why they have not grown or gotten any stronger. Your body only adapts to the amount of stress that you put on it. If you can bench 250 lbs. for 6 reps and you stay at that weight for three months then your chest is only going recruit the necessary muscle fibers to lift 250 lbs. As a result, your muscles will adapt to only lift 250 lbs. Keep a log to keep growing.