Saving $100 a week from age 25 could give you over $1 million when you retire

• The key to a comfortable retirement may be saving $100 a week starting at 25.
• Doing so could amount to over $1 million by 65, a new report found.
• Student-loan-payment resumption means millions of Americans may be unable to save for retirement.

Putting aside a couple hundred dollars a month for retirement starting at 25 — just a few years after many Americans graduate from college — could amount to huge gains around retirement age.