Drawing on the PIAAC data, in this paper I examine how motivational factors such as motivation to learn and grit are related to low-numerate adults' employment status and their actual participation in lifelong learning in Germany, the United States and South Korea. In particular, the study uses PIAAC self-reported data on the degree to which the respondent "likes learning new things", and "likes to get to the bottom of difficult things" as proxies of motivational factors in adult learning. Findings show that across three countries both "motivation to learn" and "grit" have independent relationships with adults' employment status and actual participation in adult learning. Considering that low-skilled adults are the ones who need further learning the most, yet are repeatedly reported to have the lowest rate of participation in further learning, these findings highlight the "motivational factors" in adult learning. They also suggest that "motivation to learn" and "grit" may mitigate the disadvantages that 'vulnerable' adults experience due to low numeracy skills. Implications for mathematics educators and adult education research are discussed.