只好(zhǐ hǎo) - have no choice but to, be forced to in Mandarin

只好 (zhǐ hǎo) marks a fallback. Something has closed off the option you wanted, so you take the one that is left. It almost always follows a clause giving the reason, and English usually renders it as had to or had no choice but to.

Its neighbours are worth keeping apart. 必须 is an obligation imposed from outside (you must). 只能 states the only possibility. 只好 adds resignation on top: this is not what I wanted, but here we are.

The trap for English speakers is placement. 只好 is an adverb, so it sits after the subject and before the verb: 我只好走路, never 只好我走路. It also does not take 了, because it describes the choice rather than the completed action.