Text Messaging to Increase Activity in Midlife

In MASTERY, participants will have interactive, two-way text message 'sessions' (5-10 minutes of two-way text communication with an automated text-message program) once weekly for 12 weeks. Furthermore, study trainers will conduct 4 brief calls with participants (Weeks 1, 4, 7, and 12) to introduce the program, assess progress, answer questions, and provide support.

Participants in the control condition will also receive text messages once per week. To ensure time matching, the program will have 4 phone check-ins (on physical activity) as in MASTERY.