Inclusion Criteria:  INCLUSION CRITERIA FOR CANCER SURVIVORS:  >= 18 years of age Diagnosis of stage I-III colon or rectal cancer Undergone curative-intent complete surgical resection Completed all neoadjuvant and adjuvant cytotoxic chemotherapy or radiation (if indicated) prior to enrollment Owns a smart phone that has access to the Internet and can receive daily text messages Able to speak and read English or Spanish Have a support person >= 18 years of age who speaks English or Spanish and is willing to provide informed consent and support the participant throughout the study >= 4 weeks since a major surgery to start of intervention (removal of port or catheter (cath) is not major surgery; reversal of ostomy is major surgery and will require at least 4 weeks prior to enrollment) Readiness, as determined by the Physical Activity Readiness Questionnaire (PAR-Q). If there are any indications that home-based exercise might be unsafe based on PAR-Q, the patient will not be enrolled until confirmation from the patient's provider is received via email and/or phone that they are safe to exercise. Providers do not need to be contacted if patients answer 'yes' to 'Is your doctor currently prescribing any medication for your blood pressure or for a heart condition?  INCLUSION CRITERIA FOR SUPPORT PERSONS:  Identified by a cancer survivor participant who has consented to participate in Tools To Be Fit as their support person 18 years of age or older Speaks and reads English or Spanish Consents to complete two online surveys and four 1-on-1 health coaching calls during the 48 week study  Exclusion Criteria:  EXCLUSION CRITERIA FOR CANCER SURVIVORS:  People with potential contraindications to home-based exercise based on the PAR-Q for whom the investigator is unable to obtain physician clearance ACS guideline score of >= 4 out of 6 at enrollment based on self-reported diet, BMI, and physical activity. Our screening survey will ask participants to report their height and weight; usual intake of foods in the ACS guidelines (e.g., red and processed meat, fruits, vegetables, grains); and the Godin Leisure Time Exercise Survey Used a physical activity tracker and a diet tracking app for >= 1 week in the past 3 months; these are components of our digital health tool kit Planned major surgery during the study period (removal of port or cath or dermatological procedures excluded) Scheduled to receive any form of further cancer therapy during the study period Concurrent, actively treated other cancer (except non-melanoma skin cancer, in situ cervical cancer or localized prostate cancer treated with surveillance only) History of severe cardiovascular, respiratory or musculoskeletal disease or joint problems that preclude moderate physical activity. Examples include unstable angina, recent myocardial infarction, oxygen-dependent pulmonary disease, and osteoarthritis requiring imminent joint replacement. Moderate arthritis that does not preclude physical activity is not a reason for ineligibility History of psychiatric disorders that would preclude participation in the study intervention (e.g., untreated major depression or psychosis, substance abuse, severe personality disorder) or prevent the patient from giving informed consent Participating in another weight loss, physical activity or dietary intervention clinical trial. Co-enrollment in some trials involving pharmacologic therapy is allowed. Participants are also allowed to pursue weight loss and physical activity programs on their own, as long as these programs are not provided as part of a clinical trial Currently pregnant or trying to become pregnant during the study period Living outside the United States during screening and/or the 48-week study period