We spend our whole lives wishing we were someone else.
When we're little, we want to be grown up; when we're older, we wish we were young again.
If we have straight hair, we wish we had curly hair; if we have curly hair, we wish we have straight hair.
No matter how much stuff we have, we always wish we had more.
People wish they had different siblings or parents, but I bet if they had those different siblings or parents they'd want the original ones (It's all about your attitude).
Some people wish they had a job, others complain about theirs.
On and on it goes. Think about what you have before you wish for something else. If you wish you were someone else or were like something else, just realize that if you could change lives (or whatever) you most likely wouldn't be content there either.
Be thankful :)