I take 283 mg of magnesium maleate, 200 mg of magnesium bis-glyinate and 250 mg of magnesium oxide. I also use magnesium oil that I make from equal parts boiling water and magnesium chloride flakes. For me, taking multiple forms of magnesium instead of high doses of one kind works best; I tolerate it better and have better relief.
SmilingElephant - the BEST stuff ever to fight fatigue and exhaustion is D-Ribose. It's a sugar but don't worry, it doesn't seem to raise your blood sugar or cause weight gain (2 worries I had before starting it!) I take between 8 and 12 grams per day, in 4 gram dozes. If it's a good day, I just take a morning dose and a dose at supper. If it is a bad day for feeling so tired, I add a dose at lunch time. Staying active helps me be stronger too. I started with walking indoors for 5 minutes at a time. Before I broke my foot, I could walk a couple of miles on a good day. My foot is still broken, so my walking is limited to just normal daily getting around, no "exercise". So I do a lot of stretching and lifting very light weights. I also use those elastic physical therapy bands too. Exercise started very gently and built up over time keeps me strong and helps my endurance and the quality of my sleep improves. Just don't over do it! If I do, then I regret it for days and days.