Workout Update: 645 Cardio/Lift 4 Hybrid: Day 45

On day 45, I did the 645 cardio routine in the morning and Lift 4's shoulders and arms workout in the evening. The Luft 4 workout was a circuit workout, and even though it did not have a HIIT component, it was tiring because there were almost no breaks in the entire workout (aside from 30 seconds between the blocks and at the end of each set of four exercises within the blocks) and because of the three-exercise burnout block at the end.