If your New Year's Resolutions include an exercise program, START by taking a close look at the BOTTOM of your shoes. If they look like mine in the picture above, get thee to a shoe store before you get moving with your walking/jogging/running plan. Note the smooth areas (not to mention the circular area trying to be an actual hole)- that means I have completely lost the tread and traction in that area.
Are new, good quality running shoes necessary? YES. After two decades of private practice (and seeing hurt knees, hips and ankles that might have been prevented with proper fitting footwear), my mantra is "yes, new shoes may be expensive, but NEW SHOES are cheaper than NEW KNEES."
If you are walking or jogging regularly for exercise, odds are good that you should be replacing your shoes every six months...even though the "shoe still fits"- meaning you have no foot pain, and the tops may even look "practically brand new".
PS. I strongly encourage you to head to a local running shoe store with experienced and knowledgable sales people to be properly fitted for shoes. They should not only measure your foot, but watch you walk/run/jog to help advise you on your shoes. Locally here in Austin, I recommend Ready to Run.