I found something interesting today.
It's called Magnum Lily and the protagonist is called Yuri.. I know I know, no need to say anything about that, but look at those abs!! and hey, is about boxing! You can see some raws here
In the first chapter, the protagonist gets "dumped" by some dumb guy (well, they weren't dating in the first place) and that triggers the encounter with another girl and one thing lead to another so now it's time for hot blooded boxing and muscles
I was going to talk about this in the Teppu thread but I think it's better here... If I find more interesting mangas maybe I could share more.