Interested employees will schedule a day and time to complete a health screening at a "Health Fair" at their place of employment, to ensure that they are healthy enough to participate; at this time participants will also complete the investigators baseline dependent measures, and receive a pedometer. After a one-week baseline period during which they wear the pedometer and the investigators establish their typical number of steps per day, eligible participants will then be assigned to one of four treatments - a "no incentive" control condition, and three conditions in which they are entered into different kinds of monetary lotteries if they have met their step goals for that day. Participants' initial goal will be based on their steps during the baseline period, and the goal will increase by 250 steps each week, for a total of 12 weeks. After these 3 months, the incentives portion of the experiment ends, but participants continue to wear their pedometers and upload their data for an additional 6 months. At 3 months, 6 months, and then at the study end at 9 months, participants again complete the investigators dependent measures at follow-up Health Fairs at their place of employment.