A funny thing happened after Sean Astin wrapped his grueling two-year Lord of the Rings tour of duty: He lightened up — mentally and physically — for his role in the Adam Sandler-Drew Barrymore comedy 50 First Dates (due out in February).

"I lost a lot of weight and am in much better shape," he tells TV Guide Online of his Dates gig, which has him playing Barrymore's gym-rat brother. "[My character's] doing splits all the time and push-ups and jumping jacks and lifting things. He's supposed to be this incredibly muscle-bound guy, but I'm not really that muscle-bound, so it is a joke on that level, too."

After spending so much time wearing dusty cloaks and donning hairy foot prosthetics for Rings, Astin also relished the opportunity to go completely over-the-top with his character's look. "He wears workout clothes with silly parachute pants," the 32-year-old says with a laugh. "And the tan that [I have] in the movie makes George Hamilton look like an albino. And I speak with a lisp for sort of shameless comedic purposes.

"I loved that I was given the opportunity to be so outrageously comedic," adds the Goonies alum, who is generating some serious Oscar buzz for his heartbreaking turn in the Rings climax Return of the King. "I hadn't really had that opportunity in my life before." That said, Astin remains critical of his Dates performance — and he places the blame squarely on the shoulders of costars Sandler and Rob Schneider. "I started to really show my chops but then I got a little nervous around [them] because they are so funny. I think I pulled up a little bit short of what I'm really capable of."