I'd be interested to know if they tried you on liothyronine (Cytomel/NP Thyroid) or Armour Thyroid. Blood TSH, T4, or T3 are not always a good measure of thyroid function.

Maybe this isn't your case, but many people who take Synthroid just end up feeling hot, becoming heat intolerant, and/or losing weight without a real increase in energy.

Seizures are often related to metabolism as well. It is theorized that the brain's ability to use glucose for fuel has been compromised, much like what is happening with diabetes.

Yes, occasional high-intensity running will often give many more benefits without the negatives of long-distance.

And don't forget sunlight. Super underutilized.