He said: "There are a lot of footballers who get a reputation for sitting on their contracts, but there are a lot of players out there who just want to play.
"You can earn money, but if you are not playing the game that you enjoy training and preparing for, then it doesn't make a difference.
"You want to play, that is the bottom line, and that's what I want to do."
Constantine is Stuart Gray's third summer signing.