What does ‘change yourself’ mean?

To change your life, you have to change yourself first.

What does it mean to change yourself?
Does this mean becoming someone else? Or does this mean changing your outer appearance, like hairstyle, skin colour, or body shape?
 
No, absolutely not. Changing yourself means changing your inner world, which includes your thoughts, feelings, perceptions, beliefs, etc. Changing the way you see the world, changing the way you see yourself.

Your outer physical reality is a reflection of your inner world.

You can relate it to a mirror. When you look in the mirror, you see a reflection of yourself. If the reflection face is angry, then you do not go over to the mirror and try to make the reflection smile, right? The only way to make the reflection smile for you is if you decide to smile first.

If you stand in front of a mirror with the attitude that, “I will not smile unless I see the reflection smile,” then you will be waiting forever. To get the reflection to smile, you have to smile first.

The same thing happens with your outer physical reality. Your outer physical reality is nothing but a reflection of your inner world. You can’t change your physical reality unless you change your inner world. Trying to change the outer physical reality instead of changing the inner world is like you are cleaning the mirror to get a different reflection. 

So, do the inner work to change yourself. When you change, the outside reality has no choice but to change, just like the reflection in the mirror.

I hope I could make you understand through this mirror example.