In a recent address, BlackRock CEO Larry Fink voiced concerns about the U.S. retirement system, noting it was "under immense strain." No single issue is the cause, but a combination of issues, including an aging population, rising costs of living, and higher life expectancy, is contributing to the situation.Despite Fink's concern, many Americans can still ensure they're prepared to take on retirement without a financial burden looming over them. Though not 100% foolproof, these are three time-tested ways to ...