This study aims to see if a new approach called "Exercise Forecasting" can help people with jobs with a lot of sitting get more active. It also tests if using this method in personal motivational messages makes it easier for them to exercise.

The main questions it aims to answer are:

• Can "Exercise Forecasting" be used effectively for people in jobs requiring long periods of sitting?
• Do these tailored, proactive messages encourage people to exercise more and sit less?

Participants will:

• Wear the provided smartwatch and answer two questions per day
• Receive customized motivational messages

Inclusion Criteria:

• Can communicate in English
• Currently participate in less than 30 minutes of regular physical activity per week.
• Healthy male/female, age >=40
• Currently working in a prolonged sitting job (e.g., truck driver or office worker).
• Have been working in this industry/business for at least one year.

Exclusion Criteria:

• Have had a heart attack within the past three months
• Surgery in the past three months
• Recent stroke, mini-stroke/TIA in the past three months
• Recent seizure disorder or epilepsy in the past three months
• Had an aortic aneurysm before
• Have a medical condition or physical limitation that makes physical activity unsafe
• Currently meeting or exceeding physical activity guidelines (≥150 minutes/week of moderate-intensity activity or equivalent).
• Cannot wear a smartwatch for 30 days.
• Do not want to install a study APP in smart phone for 30 days.
• Cannot respond to the study APP notification for 30 days.