In my early twenties, I had no idea what was happening to my body: I was experiencing brain fog, fatigue, body aches, and heart palpitations. It turns out, after taking a blood test, that I had a thyroid disease.

In a way, I was lucky. I didn’t have to wait the typical amount of time it takes for a thyroid disease to be discovered. I found out right away, which let me get a jump-start on finding treatment and building a routine for myself.

A thyroid disorder is a dysfunction of the thyroid gland (which is a teeny-tiny gland in the base of the neck). Some people’s glands produce too much thyroid hormone (known as hyperthyroid), while some produce too little (known as hypothyroidism).

My specific thyroid disease, called Hashimoto’s disease, is an autoimmune disease in which the body mistakenly sees the thyroid as a threat. My body attacks the gland, slowly killing the thyroid and its ability to produce and dispense crucial hormones (these hormones are called T3 and T4). It can lead to both hyper and hypothyroidism. I take medicine every day, and I will for the rest of my life.

Related: What It’s Like To Have Arthritis In Your 20s

It was also in my early twenties that I first began exercising. I had started working out after a lifetime of sloth-like behavior (seriously, not an exaggeration) because I wanted to get fit and be strong. Sure, I was skinny, but I had no muscle tone and little strength or endurance. I wanted to feel powerful.

I take medicine every day, and I will for the rest of my life.

I began exercising with 25-minute workout DVDs in my living room. Immediately, I felt how easily exhausted my muscles became—they really burned! They also seemed to lose all strength if I demanded that they do the slightest bit of work.

I found that thyroid disease could cause muscle weakness and cramps. I had my blood levels drawn (which is how the doctor checks if the medication is working to control the disease) and my levels were good. So why was working out so excruciating, I wondered.

According to the American Thyroid Association, patients like me can have problems with types of anemia. So, back to the doctor I went to have more blood drawn. Sure enough, I was anemic.

This was the first time I learned what it truly meant to have a chronic disease: The body is often affected in a myriad of ways your doctors may not tell you all about, so it’s up to you to do the research when your symptoms don’t make sense.

Related: How To Become A Runner When You Think It’s Not Your Thing

After introducing liquid iron into my daily routine, I began to feel stronger, and my workouts became easier and more productive. I was exhausted at the end of a session, but in a clarifying way, not a weak way. I amped up my workouts and added weight-lifting at a local gym.

Exercise became addictive. Not only was I increasing my physical strength, but I was awakening my mental and emotional strength. I felt better.

It’s up to you to do the research when your symptoms don’t make sense.

I also took up running after a lifetime of believing I was bad at it. I realized I wasn’t “terrible at running,” (a common myth people seem to buy into), but I also didn’t start out doing two miles at full steam ahead; I had to pace myself. Once I got going, though, I found it so invigorating that I ran farther and faster every week.

Then something changed. As I pushed myself, I realized there’d be days I just couldn’t work out. I’d exercise with regularity, and then one morning I’d wake up and be absolutely wrecked. My muscles would be incredibly weak, and I’d slog around in a fatigue so profound I could sleep all day.

This would sweep over me for a day or two, and then I’d feel more or less okay again. I began keeping track of these episodes, and realized that when I pushed my body hard, it pushed back.

With some research, I found that people with my disease can also often be low on certain nutrients that are crucial for physical resilience, such as vitamin D and B-12. And, according to The Journal of Applied Psychology, running causes short-term inflammation, which then causes red blood cells to work less efficiently.

Back to the drawing board: I added a B-Complex supplement and a vitamin D to my daily supplemental regime, and I cut back on how many days a week I ran, giving my body more time to recover.

Not only was I increasing my physical strength, but I was awakening my mental and emotional strength. I felt better.

Related: Shop exercise accessories to boost your workout success.

Including a wider range of exercise allowed me to be flexible with my routine; if I’m feeling tired and sore one day, I can do Pilates with a YouTube video in the place of a run. Easing up when my body needs it has made a huge difference in the amount of thyroid-related flare-ups I have.

Learning what works and what doesn’t in my workout routine is truly empowering. I have found that a willingness to be flexible with my workouts (while taking breaks when necessary) is the key to success.

On top of that, research and healthy eating give my body the assistance it needs to move. I will never be a long-distance runner or the best at any one sport, but I don’t worry about that. I’m moving and building health—despite my disease—and that feels incredible.