I don’t think it’s overworked - I like the handling; it looks quite painterly and not fussy.
I think it’s quite evenly handled across the painting - that might be something to consider; if you want to draw more attention to the head for example, you might increase the level of detail there, and loosen as you move away from the focal point. There is value and colour contrast against the background - so I can see you’re putting thought into it already.
Looser strokes can help give energy to a painting and help indicate movement, so if the pose is in motion it could help to express parts with broader strokes.
Keep it up - I’d like to see more!
edit: The cougar looks realistically proportioned, so I’ve assumed you didn’t mean simplification as found in character design - Like simplifying and exaggerating shapes to emphasise character?