There is nothing wrong with watching what you eat and exercising. It's a good thing that you are have picked up this habit at your age. I wish I had! There are some things you should probably question though. Are you overweight? Find out what your BMI is and go by that, you can look it up online or ask like, a PE teacher at school about finding out. The only reason you would need to eat and exercise like you are is to lose weight, not sustain it. Your eating probably isn't the best. At least you are eating more at your last meal, like you said, tacos. You might want to try to add just one or two more things throughout the day. An extra snack with different nutritional value or something more for breakfast, like a bowl of cereal. Do you eat meat with your salad? That would be a good idea or some cheese. It's good to watch your fat intake but your body does need some to be healthy and to function at it's best. Another question is, do you get hungry or are you satisfied? It's important to listen to your body. If you think you shouldn't be hungry because of what you've already ate, it's true, you may just need water. The exercising is a bit extreme. Are you athletic? Do you enjoy this? Some people do. Really and truly, to stay a healthy weight and keep a healthy body, it's only recommended to exercise aerobically 3-4 times a week. If you like to do all of these things I would suggest doing one each day of the week. Like ride the bike one day, do your crunches another, run your miles the next, etc. The reason your friends are worried is probably because you eat so little than the average person and you exercise more than necessary every day and these can be signs of eating disorders. You definitely don't want to go there so just remember to think out your choices and be reasonable. If you'd like any more advice I will do my best, just contact me. Good luck!