Phase II: Deposit contract, months 3 through 6. Phase II lasts 4 months, from month 3 through 6. The majority of study participants won't hold a deposit contract and thus won't experience an active intervention during this time. Participants who do hold a deposit contract will be free to engage with stickK as they like (e.g. write journal entries, share progress on social media), but will not receive rewards for doing so.