I still have trouble pedaling up steep hills.

Even in a low gear, my pedaling is choppy and strained. I feel almost like I'm not pedaling in a continuous cycle, but in strokes - push and push and push and push.

If I switch to an even lower gear, I either still have the problem. At an even lower gear, I just feel like I am just freewheeling in place.

Any advice? What's the best way to handle those hills (other than just avoiding them)?