Dear Daisy,
I had answers for you now. I think want to be more fit and healthy, you need to have a balanced diet every meal,eating a lot of food good for your body like: rice, vegetable, fruit, milk, body-building food,...,eat a variety of food without eating too much of anything and eat the food you enjoy, but don't have too much.
And you need to do exersice, too. We all need exersices, and you should do it every morning, walking after dinner and do exercises regularly.
I always do exercise, doing exercise and walking every morning and walking around the park in the afternoon. So I always feel good and very healthy!
That is my advices. I think you should doing like what I say to be more fit and healthy.
Love,
Dat