Troubled NFL star Aldon Smith isn't giving up his dream of getting back on the football field ... 'cause he's training like crazy in hopes of making a return to the league.
30-year-old Smith hasn't played a down in the NFL since 2015 due to a variety of issues including substance abuse, a hit-and-run and a domestic violence conviction.
Before the off-the-field issues, Smith was one of the most dominant players in the league -- he was a 1st Team All-Pro in 2012 when he recorded 19.5 sacks .