I've been thinking a lot lately of 'energy budgets'. Not, I hasten to add, anything to do with energy-as-in-power-as-in-electricity generation and its current pricing crisis. I'm talking about personal energy – our available energy to get up and do things.
Spending a lot more time watching animals has also sharpened this thought process. It's a reductive way of seeing the natural world, but a very clarifying one. Many (most?) animals devote huge amounts of their lives to acquiring food -- their principle source of energy. It's interesting to view any action an animal takes through what it costs them and what it gains them in terms of energy.
Here is my current working model:
1) Energy = Attention + Time. The biggest discordance for me comes from wanting to do something and not being able to. It often feels like a function of pure time, but that's not true -- I have lots ('lots') of time, but more often lack the spare attention to do what specifically I want to with that time.
2) You need to be generating more than you're spending. In the longer term, at least. In theory, everyone has a personal threshold of activity beyond which they're draining their reserves rather than replenishing them. Which is okay in the short term, but is fundamentally not sustainable if that's the way you're living as a matter of course. Add to this that working above that limit means that you're not only not generating energy, you're spending more of it at the same time.
3) Rest and leisure is an active process. Broadly conceiving of rest and leisure time as being what generates energy and of work or work-adjacent time as consuming it, you need to be... actually putting the effort in to do rest and leisure well. They are not purely passive time in their conception, and not all versions of them are created equal. I also find that, when I'm getting overwhelmed with work, I rapidly lose my ability to adequately benefit from downtime, which leads to a feedback loop.