When you feel sick, you prefer to sit still. This behavior pattern is not only well known, it even has a name: “inflammatory-induced sickness behavior.”
In the modern world this easily leads to a particularly pernicious vicious cycle. Modern lifestyles lead to metabolic syndrome. Metabolic syndrome produces systemic inflammation, which makes you feel like sitting still. Wanting to sit still makes what would otherwise be the most potent tool for reducing systemic inflammation—exercise—tough to bring to bear.
This rather dense article from back in 2010 describes the problem: Inflammatory modulation of exercise salience: using hormesis to return to a healthy lifestyle. It also proposes a category of solutions: hormesis. That is to say, any of a set of mild metabolic stresses that prompt a response greater than “just enough” to stave off the damage produced by the stress itself.
The result is less systemic inflammation, and therefore less inflammatory-induced sickness behavior, hence an increased inclination to move.
Or, as they say:
We therefore propose that exercise salience, the motivation to undertake physical activity, is modulated by the inflammatory status of an animal, decreasing in an inflammatory phenotype, including the metabolic syndrome and increasing in an anti-inflammatory “healthy” phenotype. The type of phenotype may well be determined by the degree of hormesis, as metabolic stressors, such as exercise, plant polyphenols and calorie restriction tend to induce an anti-inflammatory phenotype.
Besides exercise, the article suggests two other broad categories of available hormetins.
One is related to food, and consists of the obvious stuff that everybody knows: Avoid industrially produced edible substances. Consider such modalities as time-restricted eating, calorie restriction, or fasting. Include foods rich in plant polyphenols. (In other words, “Eat food, not too much, mostly plants.”)
The other is related to temperature: Expose yourself to mild cold and/or heat stress. (Spend time outdoors in the winter. Take a cold shower. Spend time outdoors in the summer. Take a sauna.)
Each of these things will produce some mild metabolic stress. As long as you don’t overdo it, that mild stress will produce a stress response greater than necessary to handle the stress itself, with the side-effect of bringing down systemic inflammation. With the systemic inflammation eased, you’ll start feeling like moving again. That puts the potent tool of exercise back on the table.
Nature has a more recent article on all this stuff, which is sadly behind a paywall.