49ers' Trent Williams: Playing until 40 is possible

Trent Williams agreed to a new deal with the San Francisco 49ers last week. Now the veteran left tackle is discussing his plans for the future. 

While meeting with reporters on Tuesday, Williams admitted that he could continue playing until his 40-years-old. 

"I think just going off of that and knowing the medicine now and the way the NFL takes care of their players now, I think yeah, I think playing until 40 is well within reach," Williams said, according to 49ersWebzone.com. "The way I feel right now, I do think I have six years in my body. But I'm not going to be unrealistic. I'm going to take it one day at a time and continue to plug away at it. But that is the goal. I have something to prove. Can I play at a high level until I'm 40? We'll see."

Williams agreed to a six-year, $138.06 million deal. He'll make over $60 million in the first three years, but the 49ers hold an option on the final three years and $77 million-plus of the deal.

If he completes the six-year deal, Williams will be 38 and will have the opportunity to sign a new deal if he's still playing at a high level.