Craigslist or Marketplace. Get a 90s mountain bike in your size. Start riding. Join a cycling club/social group. People are always changing bikes, and would be happy to let an older one go for a decent price.

It CAN be an expensive hobby, but it doesn’t have to be. I’ve been riding my $200 Craigslist special for about 1200km this year and I haven’t spent a penny on it.

Bike co-ops exist too! Check your area