He doesn’t have demons. He’s not Batman, he doesn’t struggle with inner turmoil. The nature of this character is that he puts himself last and helps the common good. So he could easily slip into a world of boredom, The blessing and curse of Captain America is that he doesn’t have that fancy an ability. He doesn’t live in another world, or turn green. He doesn’t have bells and whistles, he doesn’t shoot missiles. He punches and kicks.