Patients diagnosed with stage 3/ 4 cancer will be enrolled. After providing informed consent, patients will be asked to wear a FitBit Charge HR continuously for 8 weeks with the option to continue wearing the monitor for up to a year after end-of-study. Baseline assessments include a physical exam, medical history, and frailty assessment. The attending oncologist will rate the patient's performance status (ECOG PS) at baseline and 8-weeks follow-up. Patient-reported outcomes (self-reported physical function, fatigue, sleep, emotional distress) will be assessed weekly using NIH PROMIS from baseline up to 8 weeks from end-of-study. They will also be collected at 1 year follow-up. Wearable activity monitor data will be summarized each week for 8 weeks, and then again at 1 year follow-up. Physical activity data (number of steps, stairs climbed, active minutes, heart rate, and sleep duration) will be collected and analyzed at end-of-study (up to 1 year from end-of-study). Overall survival will also be assessed up to 1 year from end-of-study. Absolute change in physical activity levels will be correlated with change in performance status and occurrence of AEs and death to better understand the role of remote activity monitoring in cancer patients.