Sometimes you’re in the conditions you’re in because of mental or emotional issues, and require the assistance of a mental health professional to get back on track (for example, overeating from emotional trauma leading to obesity and inactivity).
Well, I would argue that actually you can, but it is extremely difficult and we aren't at that level technologically yet. Currently, the best solution for many health conditions is to optimize sleep, diet, and exercise. We will probably be uploaded into machines before a pill can replace any one of those functions.