Last week was apparently a good one to say good-bye. In the span of 48 hours, the sport wished happy trails to a quartet of fighters who ranged from solid to excellent. Nick Hein, Jimi Manuwa, Muhammed Lawal and Alexander Gustafsson all decided that it is a good time to move on to the next chapter of their respective lives.

Some of those departures are more surprising than others. Gustafsson, for instance, is just 32 years old and one fight removed from a UFC championship bout. There is no doubt he is still capable of beating good fighters within the promotion. He could be headlining European events and making healthy paychecks for a few more years. He simply didn’t feel the burning desire to work his way back toward the top, and instead decided to bow out.

To that I say, good for him. At its best, MMA is dynamic, exciting, riveting. At its worst, it is violent, dangerous, life-changing. As fans, we mostly consider the former set of traits with no regard for the latter. But for fighters, this is a serious risk, one only worth taking when you are all-in, when your body, heart, mind and soul are in total agreement that this is a thing worth chasing; that this is the thing worth chasing. Too many fighters continue far too long with only partial investment, leading to disastrous outings that may impact them far into the future. These aren’t just athletes, they are fathers and husbands, mothers and wives. They have lives past their pro careers to consider. That often gets ignored as we chart their paths through whatever organization they are calling home. Most of the time, we only focus on who they’re fighting, the result and what it will mean for their career.

This is a good time to remember that every punch and kick adds up to some toll that we can’t possibly understand, and only rarely can see. It is something each fighter must live with in silence forever, sometimes wondering if within him or her is a time bomb waiting to explode. Here’s hoping this foursome emerged mostly unscathed.

Further, this block of retirements serves as a good reminder of just how small the window is to get to the top of the sport. Gustafsson seems like he has been around forever, but really it’s been just over six years since he truly burst on the scene by beating Mauricio “Shogun” Rua to cap a six-fight win streak and earn a UFC light heavyweight title shot. His first fight with Jon Jones, the legendary UFC 165 encounter, was less than six years ago. I can remember being in Toronto for the fight, running on a treadmill two or three over from Gustafsson as he cut weight for the match, and watching the searing intensity on his face. This was a man on a mission impossible, yet in the moment, he nearly convinced me he could do it. And then on fight night, he nearly did. At that time, Gustafsson was just 26, and after taking Jones to the absolute limit, it seemed like he had the world—and his entire future—in front of him. Yet this short time later, it is over.

Lawal’s heyday lasted a bit longer, a solid decade in the major MMA spotlight starting with his arrival in Strikeforce in 2009. He briefly held that organization’s light heavyweight championship, defeating the criminally underrated Gegard Mousasi. He also holds career wins over Quinton Jackson and Cheick Kongo. He fought at light heavyweight, heavyweight and open weight. Still, Lawal was never given the opportunity to test himself in the UFC, even when its then-parent company bought Strikeforce in late 2011. A few months later, Lawal was cut with no explanation given. In the UFC’s defense, he was under suspension for a failed drug test, but then again, the UFC has hardly made an example of others who flunked tests. There was a time he had a legitimate claim as one of the best 205-pounders in the world, but just how good was he? We’ll never be quite sure.

Manuwa never reached the heights of Gustafsson or Lawal, but the man could crack, authoring some highlight-reel KOs and taking part in several memorable encounters. Still, his time as a top-level fighter lasted barely more than five years.

Hein’s window was the shortest of the group. He debuted in the UFC on May 31, 2014. Almost exactly five years later, it was all over.

Imagine if you had a chance to chase your dreams but the clock started ticking away on you from the second you began. Imagine you only had a couple of years to get there. This is not something the best fighters in the world think about on a regular basis, but the facts are, they don’t have all the time in the world. Opportunities come and go, time marches on with or without you, titles change hands with no regard for your personal problems or injuries. The window begins shutting as soon as it opens and you start to slide through. Longevity is mostly an illusion.

None of these guys made it all the way to their final destinations, yet their journeys—brief as they were—were something else. They fought, they entertained, they mattered. In lieu of reaching superstar status, leaving memories behind is a pretty good way to say goodbye, and leaving all at once is an even better way to remind us to enjoy today’s crop of fighters while they’re still here.