Remember, its like you are reaching out to shake someone's hand. You don't reach toward their face or toward their toes. In putting you are pushing the putter toward the bottom center of the chains in the "sweet spot". Feldberg recommends pushing a large phone book like a putter in order to get the push action down. I don't know if that is really necessary. But inside of 30 feet power shouldn't be the issue. If power is the issue then chances are you are only pushing with your arm instead of with your whole body. When you push putt the power is being generated in more than just your arm. You can use a slight rocking motion and a slight lean toward the basket at release in order to have your whole body pushing the putt into the basket. Inside 30 should be easy if the power is being generated from the right place. Just like on a drive, the arm by itself isn't enough to get it there. Same with putting. Hope that helps.
