The Oscar winner, 47, has been tweeting his exercise routine, kicking off the summer with a vigorous bike ride June 18.
"First ride in quite some time. Sore legs, sore ass, be worse tomorrow and the next day," wrote Crowe.
The actor gained 63 pounds for 2008's "Body of Lies," and admitted to a struggle with getting back to his "Gladiator" physique.
During his 105-day training period, Crowe's diet plan includes "taking in roughly 2400 cal/ 2600 cal incl all beverages," and intensive workouts. Crowe wrote, "body movement with weighted objects" and "sweaty 4-shirt mornings" and finally, "i'm toast."