If you try to train up to 6 hours total, 4 or 5 days per week, you will risk overtraining and make your body prone to injuries. That amount of exercise will make you feel mentally and physically drained, especially if you’re underweight. Understand the signals that your body is sending – if it’s sore, then it needs some time to recover. There is no building muscle without proper post-workout recovery, so don’t think that you will enhance your results by living in the gym. However, you’ll come back stronger once you provide your body the time it needs to recover.