Curiosity, or to be more exact the thirst for knowledge/learning drives me to do many things as well. Often times my mindset when talking to someone, oepning etc is...im gonna learn something from this, im going to figure out the social model and be able to apply what i learn this time to the time after.
In other words i start to look at each interaction as a learning experience.
As for the second question, your right its harder to find a "good" answer for it, but the truth 90% of the time is we are content with where we are. If your content with your social life, your sex life, your relationships, etc...then do nothing is an obvious choice.
The correlation between my 2 questions is that you use what motivates you to make "good enough"...well not good enough...thats simply what motivation is, raising your standards to the point you need to take action. Otherwise its human nature to do nothing when we are satisfied.
If you make enough money for your lifestyle you dont actively pursue better jobs, if youve eaten enough you dont actively search for more food, if youve slept enough you dont lay down and goto bed...and if your content with your social life you dont take action to change it.
Hope this helps.