(CNN) -- Early this year, Michael Sam made news by announcing he is gay. On Saturday, he made history as the first openly gay player to be drafted by a National Football League team. Seconds later, he made waves kissing his boyfriend in celebration as cameras looked on. 

Now, Sam has one goal in mind -- to make the St. Louis Rams' roster. 

"I'm determined to be great," he told reporters Tuesday in St. Louis. "So I'm going to train hard and try to make the team." 

As a selection in the seventh and last round in the NFL draft, Sam playing for the Rams or any other NFL team this upcoming season is hardly a lock. 

And with standouts like Chris Long and Kendall Langford, the fact that St. Louis boasts one of the league's best defensive lines -- the place where Sam starred at the University of Missouri -- makes his task even harder. 

That challenge isn't lost on Sam, who some experts thought might not fit in the NFL not because of his sexual orientation but because they characterized him as a "tweener" -- too small to play on the defensive line, too slow to be a linebacker. 

Still, he sees the chance to learn from his Rams coaches and teammates things that can help improve his game. And he seemed careful Tuesday not to get too far ahead of himself, expressing thanks for being given "the opportunity to play" but professing no certainty that he will be on the sidelines come opening day. 
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On Saturday, he made history as the first openly gay player to be drafted by a National Football League team