CARSON, Calif. – Ultimately, it came down to passion – or lack thereof.

Landon Donovan, in announcing that he will hang up his boots at season’s end, acknowledged that he doesn’t have the burning desire that once fueled him, and his "gut" told him it was time to walk away.

He called it "bittersweet" and admitted to "some sadness" but said the time was right to end his playing career.

"Last year I took a long break from the game, and that was really the first time that [retirement] was a real possibility," Donovan said during a StubHub Center news conference Thursday afternoon. "I wanted to get away and take some time to see how it would feel after getting away for awhile. I came back rejuvenated. I came back refreshed. But after a few months even of last season, I started to have some feelings of, you know, it doesn’t feel the same, there’s not that same passion, that same energy.

"So I kept going, and there was some ebbs and flows and there were some good times through the summer – I felt great, I was playing well, we had the [CONCACAF] Gold Cup, it was exciting – and then as this year started, I was enjoying myself. I was, I think, playing well, doing well, and in the last few weeks I started thinking a lot about it again. I was talking to my family quite a bit about it, and my gut just told me it was right and it was the right time."

Donovan said he made the decision before the Galaxy’s 3-0 romp at Seattle on July 28, let club brass and head coach/general manager Bruce Arena know, told his closest friends among teammates and then informed the entire team before Thursday’s training session.

It’s a decision he said that has heightened his desire to win a sixth MLS Cup championship – he’s captured three with the Galaxy and two with the San Jose Earthquakes – and served to eliminate an enormous amount of stress.

"The way I’ve felt and played and enjoyed myself [since making the decision] is reflective somewhat of a weight being lifted off my shoulders," he said. "Now it’s time to enjoy the rest of the season, and there would be no better way than to go out a champion, so that’s where my focus and my goals are now."

Donovan, who turned pro as a 16-year-old and has been the face of American soccer more or less since winning the Golden Ball as MVP of the FIFA U-17 World Cup in 1999, said the "obligation" wore on him as time went on.

"For the last few years, I haven’t had the same passion that I had previously in my career, and to some extent I had felt obligated to keep playing," he said. "And so when that obligation goes away, I realized it was just relieving, and I could just enjoy it as a player again, almost as a kid again. ... It’s allowed me now to really enjoy myself, and that’s what I want. I’d rather have three or four months of really playing well and enjoying myself than a couple years of mediocrity and not being passionate about it."

The loss of that passion, Donovan said, is "probably a natural evolution."

"I’m sure anybody who’s in one industry for that long has those feelings at times, so I think there’s sometimes the sense of obligation in people’s lives – there’s a sense that you have to do something," he said. "I’ve never lived my life that way, and I’m sure it’s not always popular with everybody, but at the end of the day, I have to live the life I want to live. And I think that’s an important thing to go by.

"I think it’s very important in life to make decisions that are best for you, best for your friends and family and, most importantly, best for your happiness. And so, at this point, this is the decision that is best for all those things, and that’s why I’m making it."

Donovan leaves a rich legacy. He’s in his 14th MLS season, to go with stints in Germany (two brief tenures with Bayer Leverkusen, the first as a teen, and a short-term loan in 2009 with Bayern Munich) and England (short-term loans in 2010 and 2012 with Everton), and is No. 1 on the league’s all-time goals list (138) and No. 2 for assists (with 124, 11 behind Steve Ralston). He could make his 300th regular-season start in LA’s game Friday night against San Jose (10:30 pm ET; NBCSN, stream on NBCSports.com).

He’s also the US national team’s all-time leader in goals (57) and assists (58), in 155 international appearances, and starred in three World Cups. He’s the American soccer player nearly everyone overseas can identify.

None of that matters much to him, in terms of legacy, he said.

Get more on LD's retirement at LAGalaxy.com

"I hope that my teammates will say I was a good teammate," he said. "I hope that my coaches will say they enjoyed working with me and having me on their team. I hope that the fans enjoyed watching and could see how much I gave to this sport over the last 16 years.

"And that’s really it. Because at the end of the day the goals and the assists and the accolades and that stuff, in the end they don’t mean a whole lot to me. But the relationships matter. ... I think my teammates have all enjoyed being around me and playing with me, and I think they know how much I’ve dedicated to this whole thing."

His announcement comes on the heels of his MVP performance in Wednesday’s MLS All-Star Game in Portland, Ore., where he scored the winning goal in a 2-1 victory over Bayern Munich.

"All I could think [in Portland] was ‘if everybody only knew what was going on,’" he said. "It was perfect."

He’s seen MLS and soccer in America grow immensely during his time in the game, and he has played a massive role in prodding that growth.

"I played here the majority of my career for two reasons," he said. "One was I wanted to be happy, and my happiness always lied in being here, close to my family. And two was I wanted to help grow the league. I always thought it was much more important to be here doing that than to go be lost in the shuffle somewhere in Europe or elsewhere. That for me was the perfect fit.

"It doesn’t mean it’s everyone’s choice, and that’s OK. But for me that was the perfect fit, and I was fortunate that I had people that wanted to come along on that journey with me."

Donovan said he plans to spend more time with friends and family, do some traveling, and that he would like to work with children.

"I absolutely want to work with kids," he said. "I spoke to [Galaxy president Chris] Klein extensively about working with the Academy, and that for me would be a really good way to come full circle. So I fully expect that will happen at some point."