There was that time I read all of Jehovah's Witnesses literature for fun, and one theme that was constantly repeated was that the sin of Adam and Eve was to seek self-mastery over their lives. Thus, the great question to be settled between God and Satan was: have humans the right to guide themselves, or do they need divine guidance? Of course, the JW position is that human choices are hopeless without God (that's the reason why JW don't participate in politics; they think humans making their own rules is a terrible sin).

So I suspect the idea of "putting my plans in God's hands" may refer to a fear of usurping God's authority by trying to be your own master.