This means that you should split up your weight lifting routine so you aren't doing workouts that last for 3 hours. Splitting up your routine so you train the whole body between 3 workouts is the right way to go for most lifters. Another matter is what muscles you should work together. This is where push pull workouts come in.
A push-pull weight training routine is one that will have you training the upper body muscles that push weight during one workout, the upper body muscles that pull weight during another, and the legs during another. Training these related muscles together during your push-pull workouts will allow you to train hard without having to worry about overtraining and being sore in muscles that will be assisting the muscles you are working during a workout.
One push pull weight training workout should have you training the chest, shoulder, and triceps muscles together. You start with the largest muscle group, which is the chest, follow with shoulder training, and finish with triceps training. Your shoulders and triceps assist on chest exercises, so by the time you get to those muscles they should be warmed up and ready to go. You also won't have to worry about your shoulders and triceps being sore since you will be training them after the chest.
Push pull workouts should also include a day where you train the upper back and the biceps. The upper back will be trained first, followed by the biceps. The biceps will be warmed up by the time you get to them because they assist on most upper back exercises. you won't have to think about biceps soreness when you train your upper back, since you will be training them after it.
The push pull workout that strays a bit because you are training push and pull muscles is the leg one. It makes since to have a leg day because the muscles of the quadriceps, hamstrings, and calves work together. Start with the quads, followed by the hamstrings, and do the calves last. You will want your hamstrings fresh for your quadriceps workout since they assist on most exercises for them. All of the leg muscles will get plenty of recovery time between workouts.
The lower back is one muscle group that can be done in different push pull workouts. You can train it with the upper back and biceps or during your leg day. Since you won;t want to have lower back soreness when you do leg exercises such as squats you may want to train it on leg day rather the back and biceps day.
Abdominal training should also be a part of a push-pull workout routine. Since they recover quicker than other muscle groups, you can do some ab training during every other workout. You can also do abs on a day off of lifting for other muscle groups.
Once you make push pull workouts part of your routine, you should quickly notice new strength and size gains.