People in their 50s are often juggling a number of financial responsibilities, from paying for kids' tuition to caring for elderly parents — on top of saving for their looming retirement.

You might feel like your life, retirement savings and finances are set in stone at this age. But this mindset can be one of the biggest financial mistakes you make in your 50s, says Autumn Knutson, certified financial planner and founder of Styled Wealth.