A client has been training three times per week in the Hypertrophy Phase of the OPT model for the last two weeks. He has worked with a repetition range of 8 to 12 repetitions, at an intensity of 80% to 85%, and rested for 20 to 30 seconds in between each exercise. He is no longer improving his strength and has expressed feeling fatigued. Which of the following modifications should be made to minimize the effects of overtraining?