While they're optimistic about the future, millennials are a financially anxious group, with 1 out of every 20 worrying about money on an hourly basis — and they say it's weighing down their careers.

That's according to the 2016 Northwestern Mutual Planning & Progress Study, which found that millennials are less likely to expect more financial crises, with 66 percent of them predicting such woes, compared with Gen Xers, 76 percent of whom foresee additional financial meltdowns, or with Americans 50 and older, 80 percent of whom expect financial woes to come.

And 86 percent of millennials (those aged 18 to 34) believe that they'll achieve their financial goals — this despite their current financial worries. But that has made them a planning generation, with 58 percent of them classifying themselves as "highly disciplined" or "disciplined" financial planners.