Dear 100 Hour Board,
In response to (^44854), I'd like to qualify Yellow's suggestion to add a suspension system.
The author noted that their mother's 10 speed is 30-some years old, about the time of the Schwinn Varsity. Bike frame design has altered dramatically over the past few decades, and many 'vintage' bikes suffer from being assembled using long abandon standards such as French, Italian, or simply being a jumbled piece of random parts.
The late cycling guru Sheldon Brown can provide a vague idea as to how complicated modernizing an old bike can be, as evidenced by the following links:
To further compound your situation, suspension fork technology really didn't take off until the early 90s, not too long after 1" threaded and 1 1/8" threadless headsets became the new standards (1 1/8" threadless is now the norm, threaded headsets have gone the way of the dodo).
In short, you're better off either working on your riding technique and position, and investing in some gloves and biking shorts to keep riding your mom's bike. Any bike shop in town is happy to help, but I've been most happy with Racer's Cycle Service (159 W. 500 N, Provo) and Outdoors Unlimited (in the Wilk by the bowling alley; if the person helping you seems uninformed, ask to talk with a mechanic.)
Additionally, consider purchasing a new bike for yourself. Don't scrimp! Big-box store bikes almost always break within a few months and weigh a ton. A good bike ($350-$700) is always a great investment, and if you can get some commuting miles in that you would normally drive, you'll improve your health, reduce our nations thirst for foreign oil, decrease local air pollution, and the gas you save can go against the cost of the bike. Since this happens all at once, owning a good bike can't sound all that bad...