Want to learn how to play piano better than the vast majority of people on Earth? You can, and it will take you only a single day. Likewise, have you ever wanted to improve your rock climbing skills such that they are better than 95% of your friends? Again, it takes only a handful of hours (at most). I learned 3D modelling last week, and it took me a grand total of three hours to make this donut:
Update: 35 hours later, I've now gotten to the point where I can make near-photorealistic phone renders. I guess that's cool:
In fact, nearly every human skill is achievable with a moderate level of proficiency within a short period of time. The problem is that most people a) don't realize this fact, and b) do not structure their learning accordingly for maximum impact.
Regarding the first: voilà! You now hopefully realize that fact. Congratulations.
Regarding the second: there are several obvious, yet little-known things you can do to increase the rate at which you absorb and comprehend information. None of them are difficult to understand. Here are a few:
At the beginning, focus on emulation rather than outright creation. Find someone good at the skill you would like to learn. Copy them immediately and completely. Your goal at this point is to learn the basic algorithm behind accomplishing the skill - not creativity or insight.
Learn from basic, highly simplified tutorials and guides. Preface any Google searches with words like 'simple', '15 minutes', 'beginner', and so on. Leave the dense technical materials for after you've gotten your PhD.
Spend the majority of your time practicing rather than reading or watching videos. If you have ten hours to learn a new skill, set aside the first three to learn the skill, and the other seven to actually practice it. You'll absorb significantly more by doing.
Focus on getting into flow—a state of total immersion. To improve your probability of doing so, turn off your phone, minimize distractions, and dedicate a chunk of uninterrupted time to learning your skill.
I used the above skills to learn photography, 3d modelling, and juggling in a handful of days after work. Each new skill is interesting, rewarding, and helps me think more creatively in other aspects of my life. I credit the diversity of skills in my toolbelt to most of my successes.