Size matters not

[avatarxprime]

In reference to Yoda getting tired, in one of the Zahn books (forgot which, i think it was spectre of the past) luke comments on Yoda getting tired from lifting the x-wing where as he was able to rebuild Vader's castle on Coruscant. He then realized what Mara had been telling him about him getting too powerful and not using the force for guidance as much as Yoda did. So perhaps Yoda uses most of the power he channels through the force for the metaphysical guidance it offers, so using the small amount of power he reserves for physical effort was taxing, but if Yoda had been as Luke had been, focusing on power rather than guidance, he wouldn't have even blinked while doing it.

[DoctorPhanan]

I remember that. And since in "I, Jedi" Corran pointed out that maybe Yoda and Ben were training Luke as a weapon, they might have not discussed the guidance aspects of the force, and rather "neglect to mention" that aspect for fear of Luke questioning his training.

[Darth Garden Gnome]

I would say the size of shit a Jedi able to more dependent on how powerful a Force user you are, rather than how "open-minded" you are, so to speak. Let's not forget, there are some people who are only mildly Force-sensitive and can barely use any of the abilities a normal Jedi can. Meanwhile, a extremely talented Force user like Palpatine can wield ridiculous amounts of firepower in the form of Force Storms and the like. It seems that the size of things you can move etc. is mostly influenced by how deeply you are connected to the Force, which is mostly a natural thing.

So, for a Force user to be able to move planets, they would have to be born with an incredibly strong natural affinity for the Force.