As WTF Years an ISTP describes the years in which he was walking through life aimlessly, mostly being perplexed by other people's behavior and his own lack of motivation.
There is no solid timeframe that can be asserted to those years, typically however they can last anywhere from your 16th birthday to your 25th. Ideally however less.
Since ISTPs are introverted thinkers first and foremost we don't necessarily have to learn by first hand experience, but can abstract and learn from the mistakes people around us make. In that sense an ISTP often knows what is going to work and what is not, based on probability resulting from an ISTP's personal life experiences. Of course these predictions don't have dead on accuracy, but the greatest likelihood of occurence.
Since tertiary functions typically only start to develope themselves later in life (mid 20's and beyond typically) we can easily fall into a rut, the infamous "ISTP rut". This rut, from here on referred to as "Dom - Ter loop" (ineffective as it may be given how much more letters that are) is a state in which our Introverted Thinking and our Introverted Intuition team up and become butt buddies, practically disabling our most important information intake function, the Extraverted Sensing.
In this state the ISTP overanalyzes and rationalizes to unhealthy degrees, denying himself to outwardly physical experiences, thus preventing him from expanding his horizon. It's a self-supplying mechanism that will only pull an ISTP down further and further unless broken manually. The state of a Dom - Ter loop typically only arises if the ISTP is in a state of cluelessness, or aimlessness. They wouldn't be labeled WTF Years if ISTPs had a direction and goals, now would they?
Breaking the loop and state of being is fairly easy however, as the ISTP has to only appeal to the bypassed function in question. It's important to realise that if one rationalizes everything away, denying oneself experience the personal growth will come to a stillstand. During a long Dom - Ter loop ISTPs often gain maturity and insights vastly surpassing those of their peers, only further alienating themselves from the people around them or their age bracket. ISTPs quite frequently get refered to as possessing "an old soul". At the end of the road however the ISTP is bound to hit a concrete wall as the ISTP has made use of all information available to him and put them into a, in his mind, working framework, thus meaning new, or unresolved problems can no further be solved without the intake of new information, which provide new angle points to view a situation from. This is where the ISTP reaches the all-time low in the rut and can become quite bitter and unstable in his apparent helplessness, as it defies the self-reliance the ISTP is used to.
As previously mentioned however, the solution is simple. Specifically appeal to your Extroverted Sensing function, forcibly at first if you must, eventually however the ISTP will gladly do it by himself and enjoy himself greatly. Extraverted Sensing is a function that pulls an ISTP into the "here and now", and most importantly, out of his head. In this mode the ISTP enjoys life for what it is in the very moment including all its perks and thrills. Some types of ISTP will forever be adrenaline junkies, constantly trying to push themselves to new limits, whilst other ISTPs take it a bit easier and are good with just working out regularly, or getting themselves exhausted in some other way.
Once the rut is broken the ISTP however finds himself in another displeasant situation. This situation more often than not is complete solitude while being completely deprived of social peers. Dependent on how much the ISTP valued social interaction prior to the Dom - Ter loop it may not be hard for him to re-establish a social life, most ISTPs however will find themselves incapable of operating and functioning properly in society and its norms. Important here is to rely on your "going with the flow" attitude and trust in yourself, while constantly throwing yourselves into unknown situations to expand your knowledge, supplimenting your growth. While the situation may be unpleasant at first, it is only a temporary state of being as the ISTPs natural awesomeness will automatically get him out of it eventually. Bottom line being, avoid to fall right back into the Dom - Ter loop just because life dealt you a blow below the belt right as you thought things brightened up. In fact, things have brightened up, but you haven't reached the end of the tunnel just yet.
Once the ISTP obtained a clear direction everything will sort itself out for as long as he won't stray from his path, in that sense, time works in favor of the ISTP and last but not least, ISTPs are known latebloomers when it comes to socializing, so do not frown unecessarily.
In that sense, keep on walking.
Erbse 19:27, August 1, 2011 (UTC)