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.

Participants will rate the utility of the physical activity text message sessions over the past six weeks on a scale of 0 (unhelpful) to 10 (very helpful).

Participants will rate the utility of the stress reduction text message sessions over the past six weeks on a scale of 0 (unhelpful) to 10 (very helpful).

Participants will rate the utility of the phone sessions over the past six weeks on a scale of 0 (unhelpful) to 10 (very helpful).

ActiGraph accelerometers are validated as measures of physical activity and have been used in numerous studies of physical activity in patients with medical illness. In this trial, participants will wear the accelerometer for one week at baseline, 6 weeks, and 12 weeks. We will report change from baseline to 6 weeks and 12 weeks in the average number of steps per day.

ActiGraph accelerometers are validated as measures of physical activity and have been used in numerous studies of physical activity in patients with medical illness. In this trial, participants will wear the accelerometer for one week at baseline, 6 weeks, and 12 weeks. We will report change from baseline to 6 weeks and 12 weeks in the average number of minutes of sedentary leisure time per day. Participants will indicate which hours represent leisure time during workdays and off days/weekends to allow us to ascertain this outcome.

The International Physical Activity Questionnaire (IPAQ) is a well-validated 7-day physical activity recall assessment for physical activity. Activity will be measured by the number of MET-minutes of moderate or greater activity per week, and change will be assessed by subtracting the baseline score from the 6- and 12-week scores.

The positive affect items on the Positive and Negative Affect Schedule (PANAS), a well-validated scale used in other intervention trials and in patients with medical illnesses, will be used to measure positive affect (Range: 10-50). Change will be calculated by subtracting the score at baseline from the score at 6 and 12 weeks. Higher scores indicate higher levels of positive affect.

The Life Orientation Test-Revised is a well-validated 6-item instrument used to measure dispositional optimism (Range: 0-24). Change will be calculated by subtracting the score at baseline from the score at 6 and 12 weeks. Higher scores indicate higher levels of optimism.

The Satisfaction with Life Scale is a 5-item scale designed to measure global cognitive judgments of one's life satisfaction (Range: 5-35). Change will be calculated by subtracting the score at baseline from the score at 6 and 12 weeks.

The Hospital Anxiety and Depression Scale depression subscale (HADS-D) will be used to measure depression. This is a well-validated scale with few somatic symptom items that can confound mood/anxiety assessment in medically-ill patients (Range: 0-21). Change will be calculated by subtracting the score at baseline from the score at 6 and 12 weeks. Higher scores indicate higher levels of depression.

The Hospital Anxiety and Depression Scale (HADS)-anxiety subscale will be used to measure depression. This is a well-validated scale with few somatic symptom items that can confound mood/anxiety assessment in medically-ill patients (Range: 0-21). Change will be calculated by subtracting the score at baseline from the score at 6 and 12 weeks. Higher scores indicate higher levels of anxiety.

The Self-efficacy for Exercise Scale will be used to measure exercise self-efficacy. This is a 9-item scale used to assess an individual's beliefs in their ability to continue exercising on a three time per week basis at moderate intensities for 20+ minutes per session in the future. (Range: 0-90). Change will be calculated by subtracting the score at baseline from the score at 6 and 12 weeks. Higher scores indicate higher levels of self-efficacy.

The Norbeck Social Support Questionnaire will be used to assess an individual's perceived emotional and tangible support. Likert scale ratings for each person in the individual's social network will be made and the average across the social network will be calculated (Range:0-4). Change will be calculated by subtracting the score at baseline from the score at 6 and 12 weeks. Higher scores indicate higher levels of perceived social support.

The 8-item subscale of the MIDUS Sense of Control measure will be used to measure internal locus of control - perceived constraints (Range: 8-56). Change will be calculated by subtracting the score at baseline from the score at 6 and 12 weeks. Higher scores indicate higher levels of perceived constraints.

The 4-item subscale of the MIDUS Sense of Control measure will be used to measure internal locus of control - perceived constraints (Range: 4-28). Change will be calculated by subtracting the score at baseline from the score at 6 and 12 weeks. Higher scores indicate higher levels of perceived constraints.

The General Health Questionnaire-12 consists of 12 items and assesses function (Range: 0-36). Change will be calculated by subtracting the score at baseline from the score at 6 and 12 weeks. Higher scores indicate worse functional status.

Mental health related quality of life will be assessed via the mental component score of the Medical Outcomes Study SF-12 (Range: 0-100). Change will be calculated by subtracting the score at baseline from the score at 6 and 12 weeks. Higher scores indicate better health-related quality of life.

Physical health related quality of life will be assessed via the physical component score of the Medical Outcomes Study SF-12 (Range: 0-100). Change will be calculated by subtracting the score at baseline from the score at 6 and 12 weeks. Higher scores indicate better health-related quality of life.

Body weight (in kilograms) will be measured by nurses. Change will be calculated by subtracting the weight at baseline from the weight at 6 and 12 weeks.

Height and weight will be measured by nurses at baseline, 6, and 12 weeks. Change will be calculated by subtracting the baseline value from the value at 6 and 12 weeks.

Waist circumference will be measured by nurses at baseline, 6, and 12 weeks. Change will be calculated by subtracting the baseline value from the value at 6 and 12 weeks.

Blood pressure will be measured by nurses at baseline, 6, and 12 weeks. Change will be calculated by subtracting the baseline value from the value at 6 and 12 weeks.