Why does everything close so early in Brussels? (And how to get things done?)

I moved to Brussels in December last year, yet I've had a very difficult time getting settled. I work a white-collar job, typically 9-7 with very little flexibility in my schedule, and I'm perpetually struggling to take care of my day-to-day errands and shopping because everything closes so early (and opening late). I'd expect this in a small town, but not in a capital city with over a million residents.

I understand things are heavily unionized and people don't want to work overtime, but why do retail shops and customer service centres have to operate on the exact same 9-6 schedule as office workers? When I leave for work in the morning, everything is closed. When I leave the office in the evening, everything is closed. I feel like I'm living in a straightjacket... and since I don't have the luxury of taking large blocks of time out in the middle of the day, I have no idea what to do. I don't want to sacrifice my vacation days, and shopping on Saturdays is frankly miserable because the entirety of Brussels is doing the same thing.

I could cope with isolated cases of this, but virtually everything is the same, from pharmacies to clothing shops, banks, post offices, government offices, swimming pools, the list goes on. Since I moved here, my personal life has ground to a halt. Sure, the beer's great, but I want to do more with my evenings than just drink.

I'd really like to know from those who live here is, have you found a secret to getting things done outside of work? Have you managed to find a comfortable existence here?