Passive stretching is an ideal form of stretching to perform with a partner. It requires the body to remain completely passive while an outside force is exerted upon it (by a partner). When used without a partner bodyweight and the force of gravity are allowed to do their thing. Passive stretching is also called relaxed stretching, for that reason. To make it work for you, extend to a position that is at the very edge of your comfort zone and hold it, allowing gravity and your bodyweight to do the rest. There is no 'bounce' of any kind with passive stretching, nor is there any push/pull motion. Find out more about Stretching for Strength and Flexibility.
Extra Credit: 30 seconds rest between sets.