I'm currently going through Dr. Andy Garrett's Authentic Growth Blueprint and this week's module is on Intrinsic motivation.
Extrinsic motivation is when you're motivated to do something based on outside conditions - expectations, power, money, acceptance - where your actions aren't necessarily in alignment with what you would do without those outside influences. It should go without saying that being motivated by outside forces not put on by yourself isn't great, especially long term. If you condition yourself to think that you can only be accomplished or successful by how much money you make, or how much power you have, there won't be enough power or money in the world to satisfy that need.
On some level, we all struggle with extrinsic motivation. And you can see figures today who saught great wealth or prestige only to have a mid-life crisis and throw it all away realizing that there is no meaning or fulfillment in those things alone.
Intrinsic motivation is having a higher standard. Not being defined by the outside world, but setting your own standards for success. It's a higher moral power that you answer to. My favorite quote by Dr. Andy Garrett in this introductory video is "Intrinsic motivation makes the only path the high road" meaning that if you're motivated by a higher standard outside of other's thoughts or opinions, it makes the only way forward, the right one.