Mondays just got a lot less blah thanks to a new offer from Dunkin'. To celebrate National Coffee Day on September 29, the coffee and donut chain is giving away free coffee every Mondays this month.

If you're a Dunkin' Rewards member, you can score a free medium coffee (iced or hot) with any purchase every Monday in September. And as an added bonus, you'll also be able to take advantage of the freebie on National Coffee Day (although it takes place on a Friday).

Not yet a Dunkin' Rewards member? All you have to do to sign up is visit the Dunkin' website and provide your full name, email address, and phone number. You'll even get a special bonus on your birthday.

With an all-new fall menu at Dunkin', this month is also the perfect time to indulge in a sweet, seasonal treat with your free coffee. Among the festive menu items you'll have the option to choose from are the Pumpkin Cake Donut, Munchkins Donut Hole Treats, and Pumpkin Muffin.

And if you still need more of your free coffee fix later in the week, Starbucks also has an irresistible free coffee offer. Every Thursday, for the entire month of September, you can get BOGO free fall drinks after 12 p.m. at Starbucks. You just have to be a Starbucks Rewards member to take advantage of the deal.

What did we do to deserve all this free coffee?!