阅读短文,回答问题
When I was a kid, I often played basketball. So I was thin but healthy. When I was about 15, I stopped playing basketball. I also started to drink a lot of drinks high in sugar and eat much more than before. Between 15 and 17, I put on a lot of weight— about 50 kg.
I didn't know how big I was until I saw a photo one day. In the photo, I had a fat neck and my stomach was out there. I hated the way I looked. I knew I needed to lose some weight.
I started to drink only water, and eat less and healthier. I ate mainly vegetables and only one piece of meat every day, and stayed away from sugar.
I also started to exercise. Every day, I ran for 30 minutes first, and then I did some push-ups (俯卧撑) for 10 minutes. I also jumped rope for 15 minutes every day.
I kept exercising the whole winter. When March came, many people said to me, "Oh, Dave, you've been a different person!"
It was true. I had lost 25 kg in three months. I liked taking photos, and I noticed the difference in my looks.
I loved the three months. It felt good to lose weight, and it felt even better to set a goal and go for it.