It is debatable.
You need FOOD, to live. You need HOSPITAL, to live.
You don't need GYM to live.
If no GYM wrecks your mention state that much, the same people making the vaccines, also offer pills for that.
The best way to protect yourself naturally is to build your health through good food and training. Exercising isn't debatable. The question is more about how much you actually do outside. The idea of going for a walk or an hour hike in Mont Royal as a standard for good physical health or fit is grotesquely pathetic.
Going for an hour walk is actually more of a recovery form of training.
Let's not kid ourselves, the vast majority of people stay the f*** inside during winter, save for the odd weekly walk/run, or wtv.
Heck, most that have equipment at home dont even use it because we do not associate home with training. It's not an environment conducive to training for most people.
And you need food to live, you actually do not need food on a daily basis and you definitely do not need UBER eats.