The trick with these kinds of things is to turn the problem upside down: instead of trying to make yourself more decisive, work on shortening the amount of time you spend being indecisive. That turns your awareness onto something that is actually happening (indecisiveness) rather than something in your imagination (decisiveness). It connects you with reality, in other words. You then have to pay attention to your day-to-day life and notice where you're being indecisive. Ask yourself "can I resolve this particular issue here and now with some action?". If so, do that. If not, its OK -- you don't have to tackle every decision immediately, you just want to reduce the amount of waffling going on. Keep doing this for a while and you'll find that your mental habits in the matter start to change.