Anyone else struggling with this?

Being very active (running, exercising) is part of who I am. I love it. I love being healthy and fit and strong. But ever since I got sick with Graves Disease in 2013, I have struggled so much with losing weight and getting strong. When I got sick, I lost all my strength. I could barely walk up four steps that went into my house. I needed help to do so. I was also too skinny- I was 78 lbs because this sickness was making lose weight, literally over night. So because I was ill, I obviously couldn't exercise. Then I went through radiation and that made me gain a ton of weight. Then they gave me medication to help with my hormones and I lost it all and got super fit and felt amazing again. But.. I continued to struggle with my hormones because of the sickness and I gained a ton again. Now my hormones are well balanced finally and I'm starting to exercise again and run but it's sooo hard. I don't have the strength like I use to and seems like it's even harder to lose the weight I want and tone up. I'll exercise so hard and see no change. It's very discouraging. P.S, I eat very healthy. I drink plenty of water. Have you guys struggle like this before?? Any tips???