Did you know that the mind and every psychological process have a measurable physical manifestation? In other words, your mind can and will greatly affect your physical body, at will. So how does this apply to weight training? Try this: Before you execute a set, think about the precise muscles you intend on stimulating.
By doing just this, you are then creating a super-enhanced mind-muscle connection. In addition, what I want you to do is that every time you perform an exercise, think about the muscle contracting and expanding. Feel it as it contracts to lift the weight and as it stretches to bring it back to the initial position. For inatance, when working the chest, contract the muscle as you move the weight up and stretch it as you move the weight slowly on the way down. For biceps, really squeeze the muscle when lifing the weight and slowly stretch it when lowering it.