Technology Interventions to Improve Outcomes After Knee Replacement

Inclusion Criteria: * Be 40-79 years of age * Had unilateral knee replacement within last 12 months * Have an Android or iOS smartphone that is accessible and near them the majority of the day * Be willing to download the study applications on their smartphone * Spend at least 7 hours/day sitting * Be English speaking Exclusion Criteria: * Have any contraindications to activity * Have a mobility limiting comorbidity * Have a scheduled surgery within the next 6 months * Do not have ≥4 days of valid accelerometer (\>=10 hours) wear at baseline.