[codingdave]

You are going to get a lot of anecdotes with a question like this because we are all a little different - there is no single answer for what works for everyone.

You'll need to be observant, and experiment a little. When are you drowsy? Does that correlate to anything else in the day, such as meals or meetings? Take note of what your routine is before making changes, then start changing one thing at a time, and stick with what works for you. By all means, use people's anecdotes as ideas for what to try, but observe results for yourself and react accordingly.

[friedman23]

Agreed, everyone is different but I do think there is some commonality in all the different responses in that you can find the answer to your lack of energy in either

sleep, diet, hydration, exercise (or general activity), and micronutrients

[rg111]

30 minutes of exercise 4-5 days a week, strictly regularly, will make a difference in any healthy person's life. I can guarantee it.

Sleep is also a big factor. More is almost always better.