The trap one can fall into, however, is having too rigid an idea of what one must do to live well.
It happens all too often that a person gets so convinced of a particular approach that they actually completely miss that they're miserable and not getting any closer (or as close as they could have gotten) to where they'd like to be. Some people identify the wrong thing they want and live towards that goal. Such people may suffer from the pains of forcing themselves towards a goal, and feelings of disappointment/loss when they get there and realise they're still not happy. Other people try to live the best life by having generally the 'right idea' about things like career, love, friendship and so on. Such people can suffer because their ideas are so set for them that they miss out on good stuff that aren't covered by their philosophies. Or because it can be hard to expose these more detailed philosophies to rigorous criticism, because you have to make time to do so.
The weird thing is, if you look at people who get life right, often they're more like drifters than planners or deciders. It seems to me that the difference between an aimless drifter and a purposeful drifter is exactly the life lesson that these planners and deciders miss out on. And it's a matter of methodology.
Some examples of purposeful drifting might be to have a criterion such as 'does doing what I'm doing make me feel happier or not?' This works by having a theory, i.e. happiness, that identifies progress towards good living or not. This works well because it allows for a standard by which to criticise what you're doing, but in fact involves very little in the way of presumptions (the problem had by the 'planners and deciders'). It also focuses narrowly on what information you actually have, i.e. your feelings about a thing right now, and doesn't delve into information you don't have such as what you'll want in the future.
Or, for another example, one can have a rule of thumb of doing something every time their life gets comfortable to shake things up. If one felt like their job wasn't challenging any more, but weren't sure what else to do, quitting forces one to try out new conjectures and gather new information. All of this again is good for error correction. This approach in particular works a lot like natural selection, since you add selection pressures to your current ideas by virtue of making things less comfortable for yourself.
'Planners and deciders' have the right idea in trying to use knowledge creation to make their lives better. That is to say, they identify possible problems and come up with possible solutions. But their problem seems to be that their approach doesn't lead to much new knowledge being created--it is set up to be biased towards their first theory, whether that be their first theory on how to approach career/love-life/whatever or their first idea on what their goals are. Similarly the 'aimless drifter' creates no improved knowledge on how to live because they 'let what is, be'. But between the two appears to be a golden mean of drifting, but with error correcting/knowledge creating mechanisms in place to improve ones situation and engage with better and better thing in life. This seems to be the approach that is needed if one wants to live well.