I agree with the previous posters. Although Yale is not as forthcoming as Harvard, according to data from Harvard’s freshman survey’s, the average admitted student had an unweighted GPA of 3.9, with more than half the students reporting a perfect unweighted GPA of 4.0 in high school. I imagine Yale is about the same. Unless you can seriously pull your GPA up, you do not have a chance at Yale no matter what your EC’s (unless you are a recruited athlete).
That said, please read this article about what colleges look for in Extracurricular Activities: https://www.huffingtonpost.com/marjorie-hansen-shaevitz/extra-curricular-activities-college-admission_b_3040217.html