...I don't see what the problem is, honestly. A lot of people here work, you know, and still practice Parkour. Likewise, you can pursue music and still practice. I will tell you this... Making a career in music is HARD. It's a lot easier to get work as a sessionalist, a mixer, a producer, a techie... anything of that sort... rather than an actual artist. If you honestly have passion for music, I'd consider behind-the-scenes work rather than in-front-of. Not that that's what you should end up doing, but get good at everything. I know some amazing musicians who've worked extremely hard... Every minute of their waking lives, they're trying to make it big. Lots of TV performances, touring with famous musicians, etc. That doesn't mean that they will or they are going to make it big. Just be wary of that.
But I'm with Sat... Your priorities are your own. You do what you feel you must. No one else can say a thing.
For the record, I'm a musician, as well. I don't care for the business, though. I write music... I play it live. We all have a good time, band and audience alike. Music is for the music, not the money. Same with Parkour. If you want to make a career out of it, feel free. Just be willing to put a lot of your energy into it. But that doesn't mean that your training should suffer, as well. You can juggle a lot of things at once, if you really care to try.