Wondering what tool I'm referring to? Your brain. In addition to its immense data storage capability (one million gigabytes, or in more sophisticated mathematical terms a petabyte), the brain is capable of performing many important (generally right-brained, i.e. interpersonal, emotional, or creative) tasks much quicker than a computer. For example recognizing faces, feeling empathy, accurately discerning what particular tones of voice communicate, or producing sounds (vocally or instrumentally) that properly convey the emotions in a lyric or a composer's intention in the nuances of crescendos and decrescendos.
Then there are all of the unconscious functions that our brain performs - regulating breathing and heart beat, eye blinks, sexual arousal, coordination, and balance. The thrust of today's posting, though, is on the conscious part of the brain, which I'll (somewhat inaccurately) refer to here as the mind. Rather than getting tangled up in definitions, let me get on to my main point. Caveat: I am vastly simplifying a complex process here, perhaps even ludicrously slow, but repeated exposure to the idea presented here will sink in and will make a difference.
We all waste a good deal of the mind's power when we ruminate, or worry about or rail against situations over which we have no control. If you were able to accurately observe the percentage of a given day's thoughts that are focused on things you can't change you would probably be very surprised. So, step one in improving the efficiency of your mind is to improve your ability to notice when your thoughts have strayed into this non-productive area. How to do that? Simple. Practice. Practice what I can best describe as "stepping outside yourself" every once in a while, noticing what you're paying attention to, writing down the basic theme of the thought (writing is more accurate than merely thinking about it) and then practice determining whether spending time thinking about that thing is "worth it." And if so, how much? In other words, are the thoughts likely to be at all productive, or at least slightly? Just contemplating this question will open up new vistas. But for the habit to stick you will most likely need to practice a lot since virtually no one in contemporary culture really talks about the inefficiency of this kind of thought. We're used to "mind wandering."
A whole category of thinking that falls into the unproductive category is focusing on the past - what you did wrong, what you wish you hadn't said, how things could, or should, have been different than they turned out. Now it's true that you can learn from past mistakes, and a total lack of reflection on past actions would be taking things too far in the other direction. But most people way overanalyze past actions and interactions, going over the same territory dozens or even hundreds of times. The same thing can be said about the future; far too much of our mental energy is devoted to envisioning outcomes over which we have no control, or are highly unlikely to occur at all. Of course focus placed on steps to be taken to avoid the undesired outcome is valuable, but if you're observant you'll see that much, or more likely most, of your future-oriented thinking doesn't fall into that category.
Step two in improving your mind's efficiency is to practice shifting your mental focus. A particular form of meditation is an excellent way to strengthen this ability. The meditation that I recommend to my clients is to breathe very slowly and very deeply through the nostrils (or through pursed lips), concentrating on the subtle feeling of the air passing. Very suddenly a thought will pop into your mind (minds are always producing thought). Notice that it has appeared but don't judge or analyze it. Just return your mental focus to your breathing. Do not try to "empty" your mind of thoughts; the whole point here is to notice how insistent the thought-generating process of the mind really is. Practicing this meditation for ten minutes a day will significantly strengthen your "mental focus muscles," but just as with the muscles of our body increased strength will take time and effort.
To summarize, notice what your mind is engaged with, categorize that engagement as either useful or not useful, and if the latter shift your focus away from that topic and on to something more productive. As this process relates to career, you might spend time proofreading a document, rehearsing a presentation, adding a name to your LinkedIn profile, contemplating the competitive environment, researching cheaper suppliers, writing Christmas cards to clients, etc. Harnessing your mind's immense capacity so that more of it is focused on practical steps you can take to enhance your career will most likely be of even greater value to your career progression than an advanced degree!