True Muscle Trainer: Phase 1, Day 20
If you're legs aren't too sore and you feel like you need to spend another day in the gym, take your dog for an extra-long walk.
There are a lot of people in the fitness community who think if some exercise is good, more must be better. I'm here to tell you that mentality is just not the right one to have. If you're training your body to grow muscle, build strength, and increase work capacity all at once, then you're going to need rest. Change happens during rest, not during work.
In Phase 1, one day of full rest is mandatory. The other two can be "active rest" days of low-impact cardio, swimming, walking, hiking, or yoga. If you must go to the gym, then I suggest a "bro" day of arms and abs.
You may be used to doing one or two workouts per day, but I don't think doing that sort of volume is the correct way to bring results, especially if you want to build and maintain those results in the long term.
These workouts should be intense and difficult. If you can get through them without breaking a sweat or breathing hard, then you're not doing your job. Work hard when you train, and then allow your muscles to do their job when they're resting.