Depends on if it's something I care about or not. It's one thing if it's a friendly game of basketball. I'll play at the same intensity as everyone else, won't call any fouls, travels, and will be calm and gracious the whole time. It's because I don't care about being good at it. But if it's something I am serious about, I will try my hardest to win, raising my level of concentration to the highest degree I'm capable of, spending hours upon hours training/studying it in my free time, and never, ever "go easy" on anyone. My approach is that if I'm going to do something, I had better be really good at it. Doesn't matter what it is, as long as I'm investing time in it. My goal as a kid was even to crush the opposition in head-to-head contests so badly they wouldn't to compete anymore, and in other contests, beat their results consistently, again and again, until they knew I was better. Sports, academics (especially math), street fights, chess (I was one of the top 15 in the US for my age as a teenager), whatever. A couple of years ago, a friend of mine introduced me to an online card game called Spectromancer, with about 10k people playing at the time. I thought it was a really neat strategy game, but started out as a fairly mediocre player, making weak moves. After hundreds of hours playing online, thinking about it, and discussing strategies with a few like-minded people, I cracked the top 10 players in the world. Nerdy? Sure. But I cared about it and wanted to be among the best. Obviously, it can't go that way for everything; I was a lousy poker player, and simply decided to quit after a few months of playing (made money overall, but not much). But in that case, I didn't really have that love and passion in the first place; I thought the game was boring as shit, but a way to make money from rubes. So if there is something I enjoy and want to invest time in, you had better believe I am going to be very "competitive" about it. I don't really understand how anyone can have a different mindset, unless there's nothing they truly love, or they're too scared of looking poor compared to others.
It depends on my competition. If their is a loud mouth asshole on the other team you can guarantee I am going to play my guts out to shut him down. However if everyone else stays tame I usually follow suit. The sport I played the longest and went furthest with was baseball. I definitely was not horribly competitive with it. As long as my average and numbers were solid I was pretty content, not the best attitude but it kind of came with the sport. Anyone who has done jiu-jitsu knows that you can't be that competitive when you first start. I only ever went as high as blue belt but on my journey there I was probably tapped ten thousand times, including embarrassing losses to sixteen year old kids and 120lb weaklings. You have to check your temper at the door for that sport.