This is more of an advanced application of the Pareto Principle from my previous post. Using the analogy of tests, different tests may cover the same content in some way or other. This is very useful because that means you’re using your time efficiently! I call this ‘carryover’. (The ABCD part in the venn diagram)
Imagine learning a particular language, take English. There are some things that will probably carryover when learning a different language. That may be easy things like borrowed words, or something a little more abstract like the position of nouns and adjectives.
The difficult 20% that we need to work for may be a part of the 80% of a different problem. Making it easier to attain in a different situation. Nonetheless, if you want to get better at English, practice English. What I’m saying is if you have multiple goals try to ensure they come under the same theme. There’s nothing wrong with learning a little Chinese too with its Subject-Verb-Object structure (if chinese is useful for you).
Everything you do should come together and the more carryover the better; (largest ABCD is best). Strength training, nutrition, and general health are forms of mathematical problems for me. I study them because I can programme cycles better; how to optimise my energy systems and things like that.
A part of general health is social health, which is also a religious responsibility for me. A great tool for spiritual development is travelling. Maybe as a holiday with friends or if there’s a mathematical conference or someplace worth going to, to help me learn and grow I go there. Everything you do should go hand in hand. But that means sacrifices have to be made. I can’t dedicate my time to being a magician or literature. I’m not going to travel the world just for the sake of it.
TL;DR You’ll be more efficient and grow more if your hobbies go hand in hand
PS There’s nothing wrong with not picking hobbies that go hand in hand, enjoyment is a value greater than efficiency