Возможный ответ:
Now, I'm going to give a talk about keeping fit.
To begin with, keeping fit is an important part of a healthy lifestyle. As far as I know, doing sport is very important for modern teenagers because it helps them stay healthy, energetic, and strong. Besides, regular physical activity reduces stress, improves concentration, and helps teenagers feel more confident.
To tell the truth, besides sport, young people do many other things to keep fit. For example, many teenagers try to eat healthy food, drink enough water, and get enough sleep. Some also practise yoga or meditation to relax their mind and body.
As for me, in my free time, I enjoy playing football with my friends because it is active and fun. I also like riding my bike and going for walks in the park. I find these activities not only enjoyable but also good for my health.
However, I don't always have time for sports because of my homework and exams. But I try to stay active whenever I can.
In conclusion, I'd like to say that I have a positive attitude to doing sports activities. I believe that keeping fit helps us feel better and live longer, so everyone should find time for physical activity.
That's all I wanted to say about keeping fit.