If everyone has a unique connection with the Force, and Anakin has the greatest connection of all, then doesn't this line actually mean, "be mindful of yourself," but just as importantly, "be mindful of Anakin"? Isn't "Living Force" a metaphor of a metaphor? I think that Qui Gon's opening lines take on greater significance if seen this way. He's telling Obi Wan to literally mind himself, and while not aware of it, to also literally mind Anakin. Pretty clever, I think. The entire saga is contextualised at this moment. The shortcomings of everyone are highlighted. If Qui Gon's innate philosophy can be taken as "true", then no one quite measures up: Obi Wan fails to properly train Anakin, Anakin fails to restrain himself, Mace fails to see the Dark Side in himself, the Jedi fail to suss Palpatine out until it's too late, Shmi fails to see the emotional trauma of sending Anakin away at his age and even Qui Gon isn't mindful enough to understand the true effect of Anakin leaving at the age he does. What do you think?