乐趣(lè qù) - pleasure, delight, the fun of something in Mandarin

乐趣 (lèqù) is the pleasure you get out of an activity: the fun of the thing, not the thing itself. It sits in fixed patterns worth learning whole. 找到乐趣 is finding enjoyment in something, 生活的乐趣 is the pleasures of life, and 乐趣在于 introduces where the enjoyment actually lies.

Keep it apart from its two neighbours. 兴趣 (xìngqù) is interest, the pull towards a subject before you start. 乐趣 is the reward once you are doing it. You can have 兴趣 in astronomy and still find no 乐趣 in the maths.

The English-speaker trap is that "fun" is an adjective for us and 乐趣 is stubbornly a noun. 这个游戏很乐趣 is wrong. The adjectives are 有趣 (yǒuqù) and the more colloquial 好玩 (hǎowán): 这个游戏很好玩. Reach for 乐趣 only when the sentence wants a thing you can have, find or lose.