3-year-old children can do a simple exercise according to their own interests, but it is not too difficult, especially for sports that require high flexibility, such as dancing. At the same time, increase reading and insist on telling stories or reading picture books to children every day. Secondly, music enlightenment can be carried out, such as singing children's songs and listening to music. In addition, 3-year-old children can start reading some picture books of mathematical enlightenment and form the concept of numbers, which will lay a good foundation for the training of mathematical thinking ability in the future. I hope my answer is helpful to you, and I wish the baby a healthy growth.