MIAMI -- Miami Dolphins undrafted rookie Mike McCray has decided to retire two days before the start of training camp, saying he was playing football for the wrong reasons.

The former Michigan linebacker announced his retirement Tuesday on Twitter. McCray said football shaped him, but he sacrificed his happiness and well-being.

"I want to encourage those reading this to do what feels good on the inside and not what looks good on the outside," he tweeted. "Also, make sure you are doing it for you and your happiness and not for others and their happiness."

The Dolphins placed McCray on the reserve-retired list. He was a two-year starter at Michigan, earned All-Big Ten honorable mention in 2016 and was a team captain in 2017.