The trouble with traditional to-do lists, when it comes to planning out life goals, is their typical focus on the small and trivial tasks, with the big picture of how those tasks will amount to a completed long-term goal being treated as more of an afterthought.
Nach encourages tackling this process from the opposite direction. Begin by thinking big. Decide on what your biggest dreams are, and start by writing those down. Not what's needed for your job, or the obligations you're tied to by your current situation, but your most ambitious goals which you'd like to achieve within your lifetime. Whether you want to become a professional athlete, travel the world, or start a business (or all 3!), this is the kind of level we mean by thinking big.
Next comes bridging the gap between high-level goals and the smaller actionable steps which can be taken to make progress. The more that's likely to be involved in working towards the goal, the more helpful it can be to break it down into milestones using sub-goals. From an extremely ambitious life-goal, if you're able to think of certain incremental achievements which show solid progress towards it, these make good candidates for sub-goals. Keep breaking down these sub-goals, until you've reached the level of steps - relatively small tasks which are actually actionable.
The above process is, of course, easier said than done. Thinking bigger than you're ever required to on a daily basis, and coming up with a plan of how you're going to start approaching these elaborate goals, is a difficult task - but a task that is undoubtedly worth the effort.
With some form of a plan in place, all that's left is to prioritise the goals, consult your to-do list for the first steps to tackle, and start moving forwards.