I was doing some reading practice in a Japanese intro book of mine and I can't translate the second part of this sentence-
二人は去年の九月に日本語文化を勉強しに来日しました。最初は日本語の勉強で大変でしたが、今は日本語もだんだんわかってきて、勉強にレジャーに忙しい毎日をおくっています。
I'm a bit confused b/c of a few reasons. I've never seen an adjective used prenominally to describe frequency/time expressions like 毎日. I don't regard them as normal nouns cuz they don't really require a following particle so I thought they were more like adverbs really. What does 忙しい毎日 mean here? Everyday, which is busy? Can you use adj. for other time words like 寒い明日? Does that even make any sense?
Also I don't really get how the に particles in「勉強にレジャーに」are being used here. Are they making the preceding nouns into adverbs, a reason for doing something, etc.
EDIT: I added more of the passage to put the sentence in better context.