Intervention components
Participants were randomized into to one of four PA intervention groups, reflecting all possible combinations the 2 (adaptive vs. static goals) x 2 (immediate vs. delayed reinforcement) factorial design. All groups received an mHealth computer-automated intervention including: a single dose of educational materials on the first intervention day, daily text messages with MVPA goals, and performance feedback with financial reinforcement throughout the 12-month intervention. Intervention components are described below.