Online Mindfulness-based Stress Reduction for Patients Receiving Chemotherapy

The goal of this prospective, waitlist-controlled, 1:1 randomized study is to evaluate if an online mindfulness-based intervention (MBI) reduces treatment-related stress levels among patients with breast cancer receiving chemotherapy. The main questions it aims to answer are: * Does an online MBI intervention reduce stress levels (measured through the Perceived Stress Scale) among participants? * Does an online MBI intervention reduce anxiety, depression, insomnia, fatigue, nausea, diarrhea, constipation, pain, and peripheral neuropathy (measured through the PRO-CTCAE of the National Cancer Institute) among participants? Researchers will compare the online MBI to no intervention to see if online MBI reduces treatment-related stress. Participants will: * Participate in an online MBI or no intervention for 6 weeks * Answer the study surveys at baseline, 7 weeks, and 11 weeks of follow-up

Inclusion Criteria: * Female sex * Age ≥18 years * Diagnosis of non-metastatic breast cancer * Treatment with neoadjuvant or adjuvant chemotherapy or plan to start chemotherapy in \