In fact, if we have the right tools and methods, we should be able to do MORE...more of what we want and more of what we have decided is important. It is really important to keep your ambitions and dreams larger than life. When you are at the stage of imagining the truly magnificent life you want to achieve, you must think big! As Joe Vitale, one of the Secret gurus, says (although he says it in Latin, I guess that makes it sound better): "dare something worthy".
Then comes the rational thinking about how to make these dreams happen. Not if, not maybe, but how. What tools are required, what help is needed, what praying (or whatever form you use to request the help of supernatural forces) is necessary, what learning is useful, what advice is worth seeking, what prioritization is helpful to make it all happen in the right order. These are the elements that allow us to do it all, even though "it" seems rather daunting and unrealistic.
So, next time you think "I can't possibly do all of this", replace that thought with a new one: "what elements do I need to put in place in order to do all of this, because I want it all".
Good luck and keep dreaming!