Ask HN: What to do when feeling low-energy/tired during the day?

I thought it might be interesting to hear what helped others. I'd consider my lifestyle pretty healthy and my sleep is good, but I often feel low-energy during the day.

- I'm exercising a lot (usually 5 days a week)

- I'm drinking coffee (2-3 cups in the morning)

- I'm getting about 7 hours of sleep per night

Is there anything specific that I should try or get checked?