I was diagnosed a year ago with Graves and started on 20 mcg Carbimazole which was then raised to 40 mcg and eventually levothyroxine was introduced.
The Graves affected my muscles very badly. I am heavily into photography and I found if I got down low or even onto my knees I just didn't have the muscle strength to get up again without holding on to someone or something.
I have done Pilates for at least ten years and I found it quite difficult to keep going at times because my muscles felt so weak. My Pilates teacher is a physiotherapist so she knew what my body was going through and how to help me. I kept going and did what I could even though some days it wasn't all that much and my legs were really wobbly and didn't always do what I was telling them to do. I also used to get the most dreadful cramps especially at night and that didn't help when I was doing Pilates as they kept going into spasms.
I also kept going to the gym, I was never a real energetic 'gym bunny' so I never did huge amounts but I liked the crowd of people who went so I drastically reduced what I used to do and carried on there, I found mentally it was good for me to keep doing the things I liked.
I totally indulged myself and rested an awful lot at the beginning and only did things I wanted to do (I'm in the fortunate position of being more or less retired)
Someone on here mentioned meadowsweet shampoo (I was on a large dose of carb for too long, ended up hypo active after being very hyper so my hair started to fall out!)
Anyway I sent for that and discovered they also do lotions for aching muscles, I started off with their foot cream, my feet were agony to walk on, that made such a difference that I bought lotions so that I could rub them onto other aching parts. They made an enormous difference to me. I also took hot water bottles to bed every night, I found that if I could keep my legs warm they tended to feel better, not always but that helped.
This all sounds grim but that was way back when I was at my worst, I have now come off the block and replace treatment I was on but by the time I did that I found I was pretty much back to normal, cycling, walking and generally pretty active so there is light at the end of the tunnel, think you just have to accept that even though you might not look it on the outside - I lost loads of weight and looked great - you are really quite ill, so be kind and patient with yourself.