Chess is more of a "mind sport" you could say, but because it doesn't affect your life all that much doesn't mean it's not a sport. Golf, like many others, is considered a sport and it's not what you would call a "lifestyle change". Sports aren't necessarily a lifestyle change, just something humans do to entertain themselves.
Actually, the term "sport" originally meant anything with rules or guidelines that humans take a part of for enjoyment, therefore yes chess is a sport. The dominant element of competition in chess is mental prowess, it's almost impossible to play chess if you're not dedicated and at least semi-intelligent so I also have to disagree on what you said about it not involving all that much dedication.
I never said that you didn't need dedication but chess isn't a lifestyle change.
um yeah, sports aren't limited to activities that require physical exertion.
Definition of a Sport
noun: sport;â€ƒplural noun: sports
1.An activity involving physical exertion and skill in which an individual or team competes against another or others for entertainment.
Absolutely not. With all due respect you don't have to put as much dedication into chess as you do with athletics. With athletics it is a lifestyle including dietary. Like two weeks before huge meets I have to eat certain things and I can't eat others. Also chess doesn't need the physical demands and training of a sport.