No_intervention: Control

In addition to using a wearable device, participants in the control arm will receive a daily notification of their step count from the previous day.

Experimental: Gamification plus social incentive

Participants will receive daily text messages on whether or not they hit their step goal.~Participants will be entered into a game, that runs for 6 months. Each week they receive 70 points. If the step goal was met they keep their points. If not, they lose 10 points. At the end of the week if they have at least 40 points they move up a level. If not, they drop a level.~They will receive twice-weekly motivational or educational text messages that highlight the effect of exercise on functional capacity in patients with HFpEF.~Participants will select a family member or friend who will serve as a support partner. We hold a 3-way phone call with the participant and partner to discuss ways they can help the participant meet their goal. The support partner will receive a weekly email reminding him/her of these approaches and updating him/her on the participant's progress including accumulated points, level in the game, and average step count.

Experimental: Gamification plus competition

Participants will receive daily text messages on whether or not they hit their step goal.~Participants will be entered into a game, that runs for 6 months. Each week they receive 70 points. If the step goal was met they keep their points. If not, they lose 10 points. At the end of the week if they have at least 40 points they move up a level. If not, they drop a level.~They will receive twice-weekly motivational or educational text messages that highlight the effect of exercise on functional capacity in patients with HFpEF. Participants will have access to a leaderboard that will include two other participants. Participants will be ranked on the leaderboard by total points over the course of the study. They will receive a weekly text message with their position on the leaderboard.