If i am exercising daily and have a good diet going, will it hurt me if i have one bad thing to eat probably per week? (a burger, steak, slice of pizza, etc.?

Congratulations on your wise lifestyle choices. If you remain height-weight proportionate (normal body mass index, BMI) and remain in good physical condition, an occasional pizza, steak, hot fudge sundae etc will do little or no harm. Indeed, such indulgences can contribute to happiness and life satisfaction, which also enhance longevity. Everyone dies, but you'll have a good run on the way there.

Compliment you for leading a healthy life style. Daily exercise is excellent as is diet with plenty of fiber and low in sugar and fat. Pizza, steak and burgers are no way unhealthy and certainly can be consumed at least once per week without making you less healthy. Thus go ahead and enjoy.

Agree with Drs. K and H. Keep up the regular exercise, maintain a healthy weight. Occasional celebration is fine. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV vaccine. Wish you good health!