You may not be able to alter reality, but you can alter your attitude towards it.
如果一个人只希望幸福,这很容易实现;但我们希望比别人更幸福,这总是困难的,因为我们相信别人比他们实际更幸福。
You can't go back and change the beginning, but you can start where you are and change the ending.