For most regular folks, the day they can retire and cash in on those 401K benefits can't come soon enough.

Normally, retirement comes when one is in their 60's, some sooner, some later. For a professional fighter, though, it usually comes sooner rather than later.

Whether it's an injury or age that forces a fighter to hang up their gloves for good, the decision to walk away from the sport they have dedicated blood, sweat and tears to is, undoubtedly, a very hard one to make.

Often times, a pro fighter tries to hang on to the glory days of yesteryear and takes one too many fights, such as the case of Ultimate Fighting Championship (UFC) Hall of Famer Dan Severn, who, at the age of 53, is still competing, losing back-to-back fights in 2011.

Via a post on "The Underground", UFC color commentator Joe Rogan, who has been around MMA for over 14 years and has developed relationships with a lot of yesterdays and today's top stars, gives his insight on just how hard it can be for a professional fighter to reach the decision to step away from the sport:

"One of the things I think about sometimes with all the great fighters that I've seen come and go is just how difficult it must be for some of them to leave behind the incredible excitement and intensity of the world of being a professional fighter and then reset your life and find yourself something else to dedicate your time and interest to. Fighting is such an all-encompassing job. It really has to be, especially at the highest levels for you to be successful. The competition is so steep that to compete at the top of the sport of MMA you really need to be completely dedicated to training and improving all day every day. When it's time to move past that and into a new phase of life I would think that for some it must be incredibly difficult. And that's not even taking into consideration how difficult it is for some of these ultra competitive guys to know when it's time to step away. What got many of them to be successful at fighting is an incredible belief in themselves that defied the odds and the doubters. In their mind often only they know what they're capable of, and in the long run they've often proven people wrong many times on the way to being a professional. It must be very difficult to judge exactly when you want to end your career. One of the many things I love that the UFC does is they use a lot of fighters as commentators, they've got Chuck Liddell an awesome position in the company - they help these guys have options. I really enjoy watching guys step away from competing and become great coaches as well. All in all, a fighter stepping away from the sport must be a tough decision for some. "

2011 was a year that saw several tops stars walk away from competing in MMA, namely B.J. Penn after his loss at UFC 137 to Nick Diaz and Matt Hughes after his first round loss to Josh Koscheck at UFC 135: Jones vs. Rampage, though he says he is simply "on the shelf" for the time being.

Most recently, Brock Lesnar, who battled diverticulitis on two separate occasions, walked away from MMA at the age of 34 after his first round loss to Alistair Overeem last weekend (Dec., 30. 2011) at UFC 141: "Lesnar vs. Overeem."

After 14 years in the game, Tito Ortiz came to the decision that he will retire this year once he competes one more time this summer. Another star who may be in the twilight of his career is Wanderlei Silva. Though he has no plans of calling it a day anytime soon, UFC President Dana White has stated he wouldn't mind seeing "The Axe Murderer" hang up his gloves.

Regardless of what leads to the tough decision, the day will come when a professional fighter has to cross that bridge and realize it is simply time to walk way.

It won't always be easy, but it will always be necessary.