I going to start as well and get anxiety over it. A close friend takes It (6years)and has muscle pains and fatigue but not debilitating and is “tolerating” it sha started with Arimidex and switched to another due to stomach pain
There are 3 so can changes

I'll be finishing up in November, after 5 years. I experienced hot flashes and some fatique (maybe from hot flashes keeping me up?). I also have osteopenia but I don't know if it's b/c of the drug, I maybe already would have had it (was never tested for it before). And high cholesterol but I've always had that. I've been combatting all by: exercising daily with pilates/yoga combo and walk 30 mins including up 5 hills. That takes care of fatique, though I do often take a 20 min nap in the afternoon. I seem to be able to get up early, get the exercise done and am productive until nap time, about 8 hrs later. I take extra calcium daily and it has kept my bone health from deterioating. I watch my saturated fats and processed foods and have been eeking my cholesterol down 10 pts at a time for the duration. All in all, not horrible! Exercise and nutrition is key (as is for all good health!). Gook luck. You've got this!