There is no one answer to this question as there are many factors that can affect the health of a tree. Some of these factors include the type of tree, the environment in which it grows, and its overall condition. However, there are certain things that can be done to help determine the health of a tree. For instance, observing the leaves for signs of disease or stress can give insight into the tree's overall health. Additionally, examining the roots for any sign of damage or decay can also be helpful in determining the health of a tree. Ultimately, though, it is important to consult with a certified arborist or other expert before making any decisions about the health of a tree.