Engaging M-health for Symptom Monitoring and Health Promotion for Women on Endocrine Therapy for Breast Cancer (EmSHAPE)

Inclusion Criteria:

* Participants must identify as a woman
* Participants must be age 18 or older
* Participants must have a diagnosis of Stage 0, I, II, or III HR+ breast cancer
* Participants must have started initial treatment with standard of care oral endocrine therapy (ET) (i.e., tamoxifen, anastrozole, exemestane, or letrozole) within 16 weeks of study registration.
* Participants must have completed surgery for treatment of breast cancer at least 14 days prior to randomization.
* Participants who received chemotherapy must have finished it at least 14 days prior to randomization.
* Speak and read in English
* Own an internet-enabled cell phone
* Capable of using the electronic pill bottle
* Concomitant radiotherapy is allowed. Concomitant maintenance targeted or biologic therapy (e.g., anti-HER2 therapy, osteoclast inhibitor therapy, CDK 4/6 inhibitor, ovarian function suppression medications) is allowed.

Exclusion Criteria:

* Metastatic (Stage IV) breast cancer
* Male gender
* Prior treatment with endocrine therapy for breast cancer
* Communication difficulties such as: Uncorrected or uncompensated hearing and/or vision impairment, uncorrected or uncompensated speech defects, uncontrolled psychiatric/mental condition or severe physical, neurological or cognitive deficits rendering individual unable to understand study goals and tasks