Time to exercise, but too tired

Hi Brooke,
I have been trying to fit exercise into my schedule. I have time in the evening but I am so physically tired! I wake at 5 am to get in my other activities like meditating and preparing for the day. In fact, I learned transendental meditation with the hope of getting more energy after work. I work without lunch or break during the day so that I can pick up my kids after school. I fast easily.
I am in bed by 8:30 because I am physically exhausted. I have a strong desire to exercise, but I am so truly too tired. I contemplated waking at 4 am to get it in since I have more energy in the morning.
What would you suggest? I feel like this is not THOUGHT problem or an FEELING problem but an ENERGY problem!