Lamar Odom -- Still Workin' On My Fitness ... Without Khloe

His NBA career is likely over ... but Lamar Odom is still working out hard -- possibly preparing his body to reenter the dating pool.

With his estranged wife Khloe Kardashian having moved on to French Montana ... Odom has been spotted working out at an L.A. gym and running along the beach in the last few weeks.

As we previously reported, Lamar has been putting off finalizing the divorce ... but maybe the fact he's tuning up his body is a sign that he's finally ready to rebound.

Fun Fact -- today's Lamar's birthday. Happy 35th!