Just started running and have some questions..?

Ok so I have decided that I want to run a 5k in the fall. I found a "couch potato to 5k" running program that I have been doinf faithfully for almost 4 weeks. Question 1: At some point will I be able to just go for a run and enjoy it...you know just go and run for 35-40 minutes and not feel like I have to be pushing myself and forcing myself to keep going. I have this fantasy that I will be taking a jog and getting lost in all these deep thoughts. Right now I am like.."How long have I been running" And question 2: (this is a little silly but)...How long do you have to run to start seeing some real changes in your body. I am tall and thin but not muscly and I am hoping my will ....well...improve. How long before I see that happen?