Feeling extremely exhausted most days ?

Many possibilities: A way to figure out what causes chronic exhaustion or fatigue is to keep a diary for 3 weeks and show it to one's primary care doctor. Diary should include things such as medicines taken, vitamins or supplements taken, caffeine / alcohol / illegal drugs used, bedtimes, wake-up times, stressors (job, home, spouse, kids, etc...), exercising, foods eaten, meal times, etc... Blood tests might be done.

Consider sleep apnea: One of the more common & under diagnosed causes of chronic exhaustion is sleep apnea. More common after 40 & if overweight the issue arises when your body does not allow you to enter deep restorative sleep stages because you stop breathing if you do for long. You can spend 9 hrs "asleep" but only get 1 of effective deep sleep. Start with your GP. Treatment is easy & effective.

Need to examine: It is not feasible to provide a meaningful opinion without taking additional history, physical examination and may be some tests. It would be prudent to see your doctor and discuss if you may be depressed. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated.