Lat pulldowns are a great way to strengthen the large muscles in your back, but many people do them with improper form (ie using your arms, not your back, to pull the bar down) or strain their neck while doing them. Try this dumbbell pull over instead.
To do it: Lie down on a bench or step, both knees bent, feet flat on the floor, holding onto the end of one heavy dumbbell with both hands.
Carefully bring the dumbbell over your head, extending both arms out with your elbows soft and lowering the weight just to the edge of your bench.
Press your shoulders down toward your hips and begin to pull the dumbbell towards your belly, keeping your arms extended the whole time. That's one rep. Try to do 15 reps in a row.
Options: You can also do this with a medicine ball or sandbag instead of a dumbbell, and be sure to keep your abs tight and avoid arching your lower back when you raise the weight overhead.