Only in the mornings when I wake up my leg muscles are excessively tired. It’s hard to continue to stand without needing to sit down for a minute. If I move too quickly also, my heart starts beating quickly and I lose my breath. I often find myself sitting on the counter to do my makeup. It varies how tired they are per day. It usually lasts 40 minutes to an hour. It’s not debilitating but makes getting ready in the morning significantly harder. I’m only 20 (f) but it’s been happening for years