1.all work no play makes jack a dull boy.
2.the activities can give us happiness,and build our body,too.
3.we are free in the vacation,join in the activities can give us more knowledge,and we are not bored.
4.We have our hobby,the activities can show our hobbies,and we can learn more.
5.Activities can help us have more chance to communicate with others.
6.we can open our eyes.
还有促进友谊和人际关系之类的