干脆 / 就: simply, might as well; I just will
【五08】语气副词 / adverbs
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
Two adverbs of attitude that stand right before the verb and show the speaker's decision: 干脆 to cut through, a stressed 就 to dig in.
干脆: "might as well", "simply", "once and for all". You pick the most direct, even drastic, option instead of dithering: 我们干脆不和他合作了 ("we might as well stop working with him"), 干脆在饭店订个包间. It is not 毕竟 ("after all") or 终于 ("at last"): it does not recall a fact, it proposes a bold choice.
A stressed 就: when the speaker says it with force, 就 + 要 / 不 + verb means "well, I will (or won't), whatever you say": 别劝我，我就要去; 我就不信. It is stubborn, defiant and very spoken, close to the obstinacy of 偏偏 ("of all things"). Don't confuse it with the 就 of sequence (我吃了饭就走): here it carries the stress, and the verb is almost always preceded by 要 or 不.
Examples
别想了，干脆现在就订吧。
Bié xiǎng le, gāncuì xiànzài jiù dìng ba.Stop thinking about it, let's just book it right now.
这件事太麻烦了，我们干脆不做了。
Zhè jiàn shì tài máfan le, wǒmen gāncuì bú zuò le.This is too much trouble, so we might as well drop it.
路上总堵车，他干脆搬到了公司附近。
Lùshang zǒng dǔchē, tā gāncuì bān dào le gōngsī fùjìn.The road was always jammed, so he simply moved close to his company.
别劝我了，我就要去！
Bié quàn wǒ le, wǒ jiù yào qù!Stop trying to talk me out of it, I'm going!
妈妈不让我玩游戏，我就要玩！
Māma bú ràng wǒ wán yóuxì, wǒ jiù yào wán!Mum won't let me play games, but I'll play anyway!
大家都说这个办法不行，我就不信！
Dàjiā dōu shuō zhège bànfǎ bù xíng, wǒ jiù bú xìn!Everyone says this won't work, but I just don't buy it!
Common mistakes
✗ 干脆地我们不去 → ✓ 我们干脆不去了 (干脆 stands right before the verb, with no 地).
✗ 别劝我，我就去。 → ✓ 别劝我，我就要去。(with 要, and 就 said with stress, the stubbornness comes through; without 要, 我就去 is easily heard as "I'll go right away").