Must one continue the prayer of a vow for life if the duration was not specified when the vow was made?

Undertaking a vow is disliked (makrooh), but it is obligatory to fulfill it if it is a vow of obedience and what was conditioned upon has occurred. A vow does not bring about what Allah has not decreed, nor does it avert what He has decreed. If you uttered something you did not intend in your heart, then what counts is what you intended in your heart. If you are temporarily unable to fulfill the vow, you are obliged to make it up. If your inability is permanent and not expected to cease, then you are liable for the expiation of an oath (kaffarat yamin).