[CerebralCerb]

Before corona started, I walked to work every day (1.5 hours in total). It's a habit I've had since I was a student too poor to buy a bus card.

A few months after this I started noticing how just walking the stairs got me tired, and how my general well-being deterioated.

I've certainly never been "fit", but walking to work is a great start. It also does not require much dedication , something which is hard to spare if you have a busy career.