I had a bad, bad cold (maybe it was flu, who knows) once where I had inflammation of the outer heart muscle that tired me, a very, very irritated spot in the throat from coughing that itself made me cough more, lingering lung inflammation, diminished taste and smell, and a scratching rough patch on my eye.
It all went away by the start of spring.
None of that laid me up as much as what happened to me the year earlier when I bruised the tendon on my big toe.
Getting the cold and the incident that caused the toe injury occurred the same month of the year, but it was well into summer before I could take a decent walk for exercise and to regain my general strength that was diminished from not being able to walk as much and as quickly as one should in order to keep healthy.
I knew a woman who had the flu (in June!) some years back who let things go because she was upset at her husband just passing away.
She ended up in the ICU and on dialysis and was told she would have long-term kidney and heart damage. Her scans and test showed damage still existed months later.
A year later her scans showed a healthy heart and kidneys.