What you're thinking of is delayed gratification. An eagle doesn't have to force itself to go hunt, because physiological processes tell it that it needs to hunt. It's the same reason you don't have to psych yourself up to go have lunch - your body desires lunch.
Humans have evolved to sometimes delay their gratification. That is, we don't hunt and eat our catch immediately, but instead we hunt and preserve the food to eat next time. This has been an immensely successful strategy, because it allows us to do things like plant crops and use that as food later. Modern society is essentially built upon delayed gratification. You go work, but get paid later.
The problem is that this delayed gratification is constantly under attack by things that you could do right now that would make you feel good. Delayed gratification tends to lead to better outcomes in the long term, but our base instincts are still about getting pleasure right now. This is why people with ADHD have no problem playing a video game for hours upon hours, but have difficulty doing their job - in the video game they get the rewards immediately, but at work the rewards are significantly delayed.
Humans have evolved to sometimes delay their gratification. That is, we don't hunt and eat our catch immediately, but instead we hunt and preserve the food to eat next time. This has been an immensely successful strategy, because it allows us to do things like plant crops and use that as food later. Modern society is essentially built upon delayed gratification. You go work, but get paid later.
The problem is that this delayed gratification is constantly under attack by things that you could do right now that would make you feel good. Delayed gratification tends to lead to better outcomes in the long term, but our base instincts are still about getting pleasure right now. This is why people with ADHD have no problem playing a video game for hours upon hours, but have difficulty doing their job - in the video game they get the rewards immediately, but at work the rewards are significantly delayed.