One of your most powerful weapons in fatloss or weight gain is to always keep an accurate record of your workouts. This will ensure steady progressions as you will be always able to refresh your memory of your last accomplishments. NO GUESSING REQUIRED!
By keeping an accurate log of exercises and weights used, when you feel "down" you will be able to see where you originally started out at and where all your hard work has brought you to, this motivational tool can be much more effective than a mirror, scales or even the way your clothes fit at times!