Knowing when to stop

Usually people talk, write, encourage about starting.  Maybe more people struggle with starting something than putting an end to something. Or maybe, focus is always on adding more and new than to subtract and eliminate. 

Leaving a book that I don't enjoy, especially the popular and most recommended one has always been a problem for me. I have realized the price for completing the book which I don't enjoy is heavy. Since last six months I have been working on breaking this habit without guilt. Not having guilt is the tricky part. 

Thinking in Bets: How to make decisions when you don't have all the facts is one the most recommended book I have came across. I liked the beginning, though the way I progressed sport references, sports stories and famous personality scandals increased so much I couldn't keep up with googling every time to understand more. Its either my sports knowledge is so weak or understanding US sports is difficult ;) I had to call it quits. I get the message from the book, which most good authors could pass on in introduction. Sadly I couldn't enjoy the book. Stories makes learning, lessons interesting, for me stories didn't work in this book. 

It does not matter whether things are hard or simple, as long as I enjoy it. But continuing on path of mental resistance with things you don't enjoy cost you most important aspect, which is time. and of course energy. 

Has it happened to you before? Not able to give up? and without guilt? What are your thoughts? Please share.