I have my hobbies quite well set, still it is hard to deal with :

My intrests are Architecture, painting, math, physics....
...guitar, japanese

*I figured out that dealing with painting, math, physics will support architecture.
*Immersion in japanese suppports learning japanese.

and when I´m really done with kanji:
*reading about architecture in japanese will support BOTH japanese and architecture.

*Playing japanese songs on my guitar and singing the lyrics will support: learning kanji, singing, learning japanese sentences and pronunciation.



*So the smaller things (art,phys, math) support architecture
*architecture in japanese supports learning japanese
*learning japanese with songs supports playing guitar
*playing guitar supports creativity and learning japanese (through lyrics)

The problem is, its very hard to switch between hobbies during one day.
And If I want to manifest small changes to the methods I use to do stuff, then it takes some time.
For example switching to partially learning japanese daily by singing japanese lyrics needs some time to get used to.

And at the most unexpected times I get burning urges to play guitar, and I seem to become addicted to guitar, I can´t think about anything else during those times...the thing is, guitar is not my priority. Seems that I have to search for some really demotivating stuff to keep me from playing guitar
Happily immersion keeps me from being away from japanese for too long.

Timeboxing helps, but it's also okay to focus on different hobbies on different days (be 'week-specific' I think would be the Getting Things Done term) and/or follow your spontaneous 'urges', and only be day-specific for specific tasks for a set portion of time.

Once you're good at being aware of how these subjects connect and the kind of moods they engender/require in and from you, just design them to connect to one another in complementary ways that allow for smooth transitions, or insert some kind of abstract 'glue' to add cohesion in some way.

Metacognition, "Deliberate practice" (K. Anders Ericsson) and "flow" (Mihaly Csikszentmihalyi).

In some sense I feel Japanese is more of a pressing issue than my degree (which doesn't require that much study really), since me finding employment when I graduate and being able to move in with my girlfriend depends on it... so I do the couple hours of Japanese a day without fail, then do my mathematics study, then the rest of my hobbies.

I wish I had the time to pick up Korean and Mandarin too. But I guess they'll have to wait till I've graduated and I don't need to study Japanese anymore...

I feel the opposite - I have my whole life to study Japanese, where as I'm only at uni once and only have 1 shot at getting a good mark. Plus will never get another opportunity to meet so many random new people and go to random events.

My priorities: Studies > Social Life > Hobbies (Japanese, guitar, online gaming)