Yeah, you're in High School and I'm in middle..but doesn't mean I can't explain why.
It's important to set goals because goals are what take us forward in life. Top-level athletes, successful business people and achievers in all thing, all set goals for themselves. Setting goals gives you long-term vision and short-term motivation . It focuses your knowledge, and helps you to organize your time and your resources so that you can make the most of your life.
Hope that helped?