the 2 above comments are excellent and a good place to start. At this point, you may want to check your diet, are you getting enough veges, a little starch, some decent quality protein and are you drinking a healthful amount of water every day, not just coffee, tea. No sugar, no sodas, please. and check the ingredients for the amount salt, how much added sugar, and how much carbs, also please watch for hidden chemicals in your food, additives like artificial color, flavor, preservative and the like (they are poisons to your body). Do your best to get 7 -- 8 hours sleep (good quality rest is important). Give it from 2 weeks to 1 or even 2 months, you should see a difference in the way you feel. If you are doing all of the above (including the first 2 comments) there should be measurable results. (Try to journal what you are doing and how you are feeling everyday). Then either see your regular doctor & take your journal with you (ask for a consultation-- you might get more time with the Doc. ) or find another DR. maybe a homeopathic Dr or the likes and see if you can get to the source. What you are going through is not NORMAL and I sincerely believe that once the culpert/s are discovered it is at least mostly fixable. Good luck and safe journey.
Walking is a low-impact activity that needs little equipment, can be done at any time of day, and at your own speed. You should go for a stroll without the dangers that come with some of the more strenuous types of exercise. For people who are overweight, elderly, or haven't exercised in a long time, walking is a perfect type of physical activity.
Doctors aren't actually fitness experts. They are health professionals. If you're telling them how much you walk, that's a problem because they are clearly not listening to you. If that's the case, you have docs who are rushing through their appointments to get them all in every day and not paying a lot of attention, which isn't all that unusual and might lead you to seek different doctors. But if you're the typical patient, you're not telling your doctors that much about you largely because appointments are usually so rushed there isn't that much time to do that. If you haven't told your docs what you're doing they won't know. Society at large also has a view of exercise shaped by the fact that most people today who live in urban civilizations work in offices or at desks and watch a lot of TV and use computers and phones much of the day and don't get outside to do heavy chores the way humanity did for most of its history. This is a fact; way too many people are largely sedentary, which is one of the worst things anyone can do for their health. The answer you are seeking is, no, if you move a lot, you don't need to exercise. Exercise will give you better tone and bigger muscles and probably be more beneficial in a cardiovascular sense than just moving when you do your everyday activities, but evidence shows that people who move are much healthier overall than sedentary people who get all their movement in one bout of daily exercise. The reason you are being told to exercise is because doctors are trained to tell every patient to exercise because they assume that otherwise they are not moving as much as we did historically. Which is true. Now, yes, there is a difference for most people between walking to get somewhere and walking for exercise. I don't know that leg warmers are a thing anymore and a speedo is for swimming, which is a whole lot better exercise than walking, but those of us who walk for exercise are usually people who are unable to do more vigorous exercise anymore or just don't want to, but we walk fast and hard, we don't just stroll. So there can be an enormous difference in energy output between walking for exercise, especially if you do hills, and walking to the store. And yes they do have a contract that requires them to do everything that they do -- it's with you, it's with insurance companies, it's with medical schools, etc. Like everyone they are trained and they follow their training, which might not actually be true information but it is what they know. I walk in clothing by the way that matches the weather and for comfort, but I advocate always wearing the least amount of clothing you can legally get by with because it allows for better perspiration and makes the body work harder to keep warm which helps add to energy output. I would avoid those silly yoga pants everyone wears nowadays because they're made of petroleum and probably promote fungal infections and go back to good old cotton sweats or very lightweight running shorts, but that's just me. But I say this because the clothing you wear to exercise is for ease of movement, whereas the clothing you wear when you walk somewhere is the clothing appropriate for when you get there and may not allow that ease. The headset is because walking is extremely boring. I walk because I can no longer run or play basketball or do much better forms of exercise because I got old and injured. If I could still do those things, you wouldn't catch me walking for exercise, but others really like it and it's all they really care to do. I'd rather really get the old ticker going, but alas, I can't. Lastly, if you're complaining of fatigue, and they've done a thorough exam of you, and that's not common, then they are assuming you don't sleep well enough or don't do enough. Exercise promotes energy. Peace.