Chael Sonnen is calling it a career.

Following his loss to Lyoto Machida at Bellator 222 Friday night, the 42-year-old announced his retirement: 

Sonnen was defeated by a second-round TKO in the co-main event. His career ends with two consecutive losses as he also fell by TKO to Fedor Emelianenko in October at Bellator 208. 

However, recent results won't deter his impact on the sport. 

Many in the MMA world sent tributes to Sonnen following his retirement announcement, including Bellator President Scott Coker: 

Sonnen's retirement appears to be bittersweet. He wrote an open letter for ESPN published Tuesday that delved into his promise to his late father that he would not stop fighting until he won a world title. 

"I'm going to keep going like this until I fulfill my promise or until the reality hits that I'm just out of time," he wrote. Given how recently the story ran, perhaps reality showed itself in the cage with Machida. 

Another passage alludes to continuing his career:

"Maybe I just fear the unknown, like everybody else, but I don't like to think about being done with fighting. It's a lifestyle -- going to practice, working hard, being with the guys, and even dieting and trying to make weight limits. Why stop? If I felt like I was slowing down at the gym or during matches, or if I felt like my goal of winning a world championship was out of reach, then yeah, I'd have a different conversation with myself. But right now I don't even think about stopping."

When speaking to MMA Junkie Thursday, Sonnen expressed a tinge of regret regarding the ESPN piece:

"[I] wish I would've kept it as a personal motivation for myself. It is a lot of pressure. ... I will either win the championship, or I will be a failure. I believe that wholeheartedly. 

"I was told when I was 17 years old by Matt Lindland, we were both on a wrestling quest at that time, but he told me, 'You cannot retire unless you win a world championship; you can only quit.' I don’t want to be a quitter."

Hopefully after some time passes, Sonnen can come to a place of peace with his accomplishments and 30-18-1 overall record.