text: have an underactive thyroid, take thyroxine daily but still feeling tired. how can i boost my energy levels? take a 100mcg of thyroxine a day and have been for the past year but still feel so lethargic all the time.  does anyone know of any supplements or any ways of boosting my metabolism? energy can also be related to how you feel about life and what people, things, stuff may be draining your energy.  are you happy with your life, do you do something totally just for you each day???  how do you bring joy into your life.  if you do all of the above and still have lack of energy then meds is the beginning, exercise and the food you eat are the next steps.  good luck and feel better.  life is to short to be not feeling 100%.  way to go to find the answers.