When you think most problems people deal with are simple and similar. Take your example, overweighted. You think the solution is simple: exercise more, eat less. Usually it's from an engineer's brain. But probably, you forgot to take your excuses into consideration, that's why you over simplified it. Then you struggled with it like many other people. If you do take all of the aspects into consideration, it's no longer simple any more.
When you easily felt bored after you have learn something new, I think it's lacking of depth to learn it more or to find more fundamental problems in it before you skip it.
I agree with you in most of the points, but I wish I could see that you can really dive into something and make it a big different for the world. If you cannot find anything with enough challenge for you, you may want to visit here: http://kck.st/JNqv8z because most people think that they are overwhelmed.