From where I stand the marathon is a paradigm for all actions that we need to take in order to accomplish something that requires some kind of physical activity. On the other hand there are things that just happen like magic.
I do need to get up and study, I do need to "build" the house I surely can't do it out of my bead or by meditating. But if I study what I really love and want to, where I dreamed to go to school.... and I have to find the land where I want to have my house built and choose the layout...materials... colors...
(But then again I could LOA an Ivy League College of my dreams.... and the Universe could send me after meditating on the perfect spot for my house somebody who needs to sell that land...the one of my dreams)
Being in physical form to run a marathon at my age need a lot of very inspired doing, but only if it is my dream
to run it.
But if it is what I attracted by LOA consciously and really want it then the action is easy and logical.