My Interpretation; Please Tell Me What You Think of It (SPOILERS)
We just watched this at the annual Boston MFA French Film Festival and My Love and I had very different interpretations.
When I find myself puzzled by a director's intentions,as I was with 40-Love, one of the things i look at is - what scenes the director chose to include , and how did those scenes affect my interpretation. My own take on this film is that the EARLY scenes of the boy at his physical exam- are key to the trajectory of the story. The doctor tells the boy's father that the boy has, ESSENTIALLY, a super-human heart, that nothing will ever wear him out. (We see evidence of this when the boy keeps pace running alongside his father's car.) This is the result of his unique LOW heart rate. It sounds like a defect, but in actuality, it is the opposite. But Olivier Gourmet, the father, does not tell the boy about his superior heart because (I believe) he doesn't want the boy to be too cocky about his innate superiority; he wants the boy to work hard.
BUT the BOY just hears 'low heart rate' and thinks it is a defect. So, we are shown many scenes where the boy fails( is not 'the last man standing') at various tennis exercises because he holds himself back, afraid he will damage himself and not be able to keep playing tennis. His coach tells him that he doesn't play like he wants to win, but he doesn't know that instead, the boy is just protecting himself from his perceived defect. Ultimately, the boy's MIND prevails over his otherwise superior stamina so that it causes him to commit the crime against his rival (because the boy doesn't believe he has the strength to win on his own.)
In the end, all the dreams are destroyed because of a misunderstanding. And the real tragedy is that no one will ever understand the boy's motivation because they don't know about the miscommunication. If the boy had been told from the beginning that his heart was a great advantage,and not a weakness, there would be no film to be made.
The way to have what we want
Is to share what we have.