The future

Nothing is set in stone.

The future is pliable, and can change with decisions you make.

It's much easier to say that you will be a non smoker in the future, if you quit now.
This part would be up to you.

I would be weary of people telling you that you cannot change-- unless they are doing reverse psychology to get you to make a change.

There are many timelines in your life, of which you can choose, so just remember you have that choice.