"It wasn't an easy step to take," Marcell Jansen, 29, told Bild. "I thought about it a lot on holiday. I had some amazing offers but for me continuing just wasn't an option."
"I can't go on playing for two or three more years when I'm not fully committed," said the ex-international. "I think I can invest myself in new projects that will be more fulfilling for me."
Speaking of his desire to found a start-up, Jansen said "it's something I've been dreaming about – and I'm going to do it. I'll go for it with 100 percent commitment."
Jansen is one of Germany's most experienced and long-serving international footballers.
After making his debut for Die Mannschaft in 2005 against Slovakia he went on to win 45 caps over a decade, appearing at two World Cups.
Despite being a defensive player he contributed three goals across his international career, one a crucial intervention in a 2-2 draw against Uruguay during the 2010 World Cup in South Africa.
Jansen started his career at hometown club Borrussia Mönchengladbach and quickly made a name for himself as an energetic fullback.
It wasn't long before Bayern Munich came calling, snapped him up in 2007 for a fee of €10 million.
But an injury plagued season with the Bavarian titans was followed by a transfer to Hamburg SV for €8 million in the summer of 2008.
After seven seasons of mixed success in north Germany, the struggling port city club decided not to extend Jansen's contract this summer.
But he still had offers from several leading European clubs, including Benfica FC in Portugal.
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Jansen indicated in his interview, though, that he has lost his passion for the professional game.
"I'm delighted that I can have my hobby back," he told Bild. "Football used to be my job. Now it is my hobby again."
But with Jansen set for a new life in the start-up scene, hipsters might want to keep an eye out for for a familiar face sipping on Bolivian coffee in a trendy co-working space.