So I made a big decision.?

See, my Grandfather loves running. He was an XC coach and Track. He just loves it. And so do I. Except, I just like watching it. I feel very obligated to do Track this spring and I dont exactly want to. The other day I sent him an email saying how I was getting in shape and I was ready for Track, but then when I got home today, I walked inside and for some reason I just changed my mind. I dont want to do track, I dont like it! But how do I tell my Gpa that? I love him. I will feel so horrible.