Does it help to list examples of the opposite, "tomorrow" or "manana" culture? Or aphorisms like never do tomorrow what you can do today?
This brings up time preference which the original article author carefully danced to avoid discussing. Uneducated or lower class thought patterns seem to yield instantaneous maximal values of happiness X. If your outlook on life is to achieve the highest value X, even if for a very short amount of time, then you won't like Stoicism due to having an extremely high time preference. On the other hand if you walk a difficult path, seemingly an unnatural unevolved superficially unemotional undramatic path, which the stoic philosophers seem to think takes a lot of training and education and generally higher class attributes like intelligence and wisdom, the resulting extremely low time preference will produce some superficially really weird and non-traditional attitudes (what does this say about tradition?) that regardless of how "weird" they are, result in a maximal value when value X representing happiness is integrated over an entire lifetime. But your super low time preference is going to result in nearly living on a different planet from people with extremely high time preference, those groups have severe difficulty communicating with each other, often totally opposing concepts of value and whats right. Basically a different culture.
Of course the stereotypes from people who don't really get it, start flowing and "naturally" its always the case that whatever is happy short term is the opposite long term or integrated over a long period, at least according to naturally grouchy people, for no apparent reason, or sometimes in defiance of reality, because it makes for dramatic philosophical texts. Of course reality has no obligation to make grouchy people consistent and happy, which is kind of funny in context. I guess I'm saying a crappy Stoic is a failure of a Stoic that wanted an excuse for being a grouchy "get off my lawn" guy, so spits out the grouchy answer off the cuff every time instead of the actual Stoic answer that might take some thought, unless its a really dumb question.
As said wonderfully by Marcus Aurelius: http://directingmind.com/meditations#8-36
To me, 'living in the moment' sounds awfully similar to the goal of Vipassana Buddhism: accurately perceiving reality (i.e. enlightenment). In that sense, 'living in the moment' is a passive rather than active act: experiencing your life without reflexively (often unconsciously) judging or labelling your experiences. Neither ruminating over the past nor obsessing over the future. Observing without judgement and thinking only when you choose to. A 'skillful' state of mind.
I doubt many, if any, of us are able to perceive things this way, without deliberate cultivation of a non-judgemental mind. I guess that's why the phrase is 'practice meditation'; it is literally 'practising' a specific way of perceiving the world (one that doesn't come naturally to us), just as you have to practice any other skill.
If this all sounds a bit strange, maybe even untrue, give this a try: go somewhere peaceful (a park, your backyard etc.) and just sit down somewhere and 'watch the world go by' for 5 minutes. Try to observe impartially, without labelling, judging or letting your thoughts drift to work, your social circle, what you're having for dinner etc. I suspect most of us (myself included) wouldn't make it past 20 seconds before some thought intruded. If you're a real masochist, try actually meditating for 5 minutes. It's torture.
If you try the above, I think you'll realise how little control you have over your own mind. I don't know much about stoicism, but maybe the stoics had a similar notion to the Buddhists. The word 'stoic' has modern connotations of outward calm and impassivity, despite the boiling emotion within. That sounds exhausting, maybe even impossible. But perhaps the original idea was similar to Buddhist philosophy: to master your own thoughts, and outward composure (maybe even 'happiness') would simply be a side-effect.
Call it GTD, 43 folders, Zen, Stoicism, in some ways it doesn't matter.
There is a lot of eastern mysticism tangled up in some interpretations of Stoicism. Arguably "when its time to X, X, and when its time to Y, then Y" given a western civ wrapper is an aspect of Stoic thought and when given an eastern civ wrapper we call it an aspect of Zen. I think I have a yearly Zen calendar hanging up with that quote somewhere. But its the same thing, presented by different theatre troops. If you're bored its possible to come up with other analogies between Zen or Buddhism in general and Marcus Aurelius or Stoicism in general. This month's Zen wall calendar quote is on the topic of correct practice means everything you observe is actual reality, which sounds vaguely Stoic I don't remember but I'm pretty sure M.A. said something like that in Meditations somewhere.
A good education means you're never really bored and always have something interesting to ponder, even if it turns out to be wrong, LOL.
The failure of emacs org mode implementing GTD, or Zen, or Stoicism is not fully applying it means unhappiness, they are philosophies of "do" not "believe" or "want" or "heard dat". So I do not have next year's Zen quotes wall calendar on my wall because I failed to input it in emacs org mode, or maybe I'm not Stoic or Zen the right way. One way or another, I'm off now to Amazon to order my 2017 wall calendar.