To me, one theory I had about hating my bike and spinning was that it was part of my "usual life". My "usual life" wasn't going so great. So, anything "usual" (including the bike & spin) was not happy "work". Try out a new class you have never did before. Or, get a guest pass to a totally new gym.
I guess the short of the wind above is: find something that helps give your life a
new purpose for "being"

.
EDIT: Lastly... after a while, you might find that those old "work" things NOW, like the bike and spin, somehow become new again after a break. FWIW... maybe a bit of hope.