Are your muscles sore or are do they feel dead, heavy, and flat? In the first instance of soreness, this is caused by micro-tears in the muscles. In the second case, of dead legs, the neurological fatigue mentioned above or glycogen depletion are the primary culprits. - Training for the Uphill Athlete
You shouldn’t train like your favorite athlete or your friends, because there aren’t two identical people, and workouts don’t produce the same effect in two different bodies. The most important thing is to find what your body needs regardless of what the other people around you are doing.