Did doctors encouraged their patients to live a healthy lifestyle including exercising and not smoking in the early twentieth century?

No
The effects of smoking wasn't really known then
Back then people ate what they could afford, and it would be cheap cuts of meat, fish and vegetables

I doubt they would of been promoting an unhealthy lifestyle and I doubt people needed lifestyle advice as much.

Absolutely not. People got exercise through work and living. They ate real food. No one knew the dangers of smoking.

I don't remember any such thing, but I did see a few doctors smoking. I DID also see ads from a cigarette company advertise that "MORE DOCTORS SMOKE CAMELS THAN ANY OTHER BRAND". And nobody said anything about that ad.