I don't believe you will be able to claim this for last year...tax rates, deductions and such are already in place.
It does look like (at least according to the author of the bill) that club memberships will be included:
"It was a tough battle, but we won it: 24-20…my Private Member’s Bill: “the Physical Activity/Income Tax Amendment Act 2008” was recently given Royal Assent! Once the bill is proclaimed, you--& every member of your family—of any age--will be able to claim up to a $500 tax credit—every year--if you participate in any ongoing
physical activity such as regularly attending a health or yoga club, or playing organized sports of all sorts. (Final details are pending…please stay tuned.) I designed this bill to be positive & proactive; to focus on promoting wellness rather than reacting to sickness; & to give us all a break on our health care costs…so thanks to all of you
who vociferously supported the cause! <Private Members Bills are seldom passed; but thankfully, going back to my “Smoke-Free Places Act 2004”, I have brought at least 2 pieces of legislation forward—every year…>"
http://www.daverodney.ca/pdfs/newsletter_jan09.pdf