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horseriding lessons
Not sure how far out of Brussels you want to be, but my daughters practically lived at the Papelotte just beyond Waterloo.
OK it was a few years ago now and things may have changed, but I'd definitely recommend them.
The Manège in my village, Nethen is highly regarded ( http://www.cenethen.be ). Both my daughters learned to ride there, one has taken here first brevette there. French and Dutch spoken (we're on the border), group lessons are 130€ for 10, ages 6 - 18.