https://www.scientificamerican.com/article/is-it-possible-to-get-fit-fast/

Everybody wants to get fit fast... but should you?

In my early coaching career, I specialized in marathon and triathalon coaching. I eventually branched out and worked with everyone from fitness models to previously sedentary seniors. But consistently, throughout my career, people would email or call and ask seemingly innocent questions like: How long will I need to train to complete a marathon?