Self-control is trainable and is applicable to learning and practicing many skills. Small, short and regular training exercises such as writing with your non-dominant hand to write or striving to maintain your posture can be a first step to build it up. (See "Can self-regulatory capacity be increased?" in Heatherton's paper at http://www.dartmouth.edu/~thlab/pubs/11_Heatherton_Wagner_TICS15.pdf.)
Yeah. I was going to say "learning how to practice", but this is more specific.
So, transferable skills: skills that, upon improvement, increase your ability in other areas (and also improve other, higher-level skills).
A basic example would be reading/writing. Knowing how to read and write allows one to access a huge amount of other skills and resources which are otherwise unavailable. A less obvious example would be clear speech (enunciation). Ability to speak clearly improves one's prospects in a lot of different areas (e.g. professional advancement, dating, etc.).
I'm looking for additional examples. Which skills did you find to be most transferable? Did you become proficient in X, and then found this helped you in many other areas of your life? Please share.
(I tried to find whether this was discussed before, and failed; if it was, I would appreciate the link.)