Especially if you have to fit your creative work around a day job or lots of family obligations, it's not usual to run out of energy. Are there some simple solutions?
Two approaches are being tested in schools in Wales right now:
1. One class of eleven-year-old kids will work with the sound of running water and rustling of leaves in the breeze in the background. (Idle thought: how many more of them will need toilet breaks?)
2. Another classroom is having the scent of peppermint piped in.
I've used peppermint tea bags in some of my all-day workshops--I hand them out after lunch for the participants to sniff, to raise their alertness. It works, although it also looks like we're all involved in some kind of weird drug abuse.
I'll keep an eye open for the results. For the moment, keep a box of peppermint tea bags by your desk and sniff when you need to boost your attention level. Doing the same with vanilla essence also works for a lot of people.
(Another way to have energy is to manage your physical and mental state. You'll find lots of useful methods in my book, "Focus: Use the power of targeted thinking to get more done," published by Pearson and available from Amazon and other online and offline retailers.)