Do it by yourself.
Believe in yourself.
Try it out yourself.
Make yourself at home.
Did you study by yourself?
Take good care of yourself.
Write in the date yourself.
Did you make it by yourself?
Help yourself to these cookies.
Please help yourself to the cake.
You should take care of yourself.
Please help yourself to the fruit.
Please help yourself to some fruit.
Before you can love others, you need to be able to love yourself.
If at all possible, you should go and look into the matter yourself.
I think it's highly unlikely that you'll be able to do that by yourself.