Be miserable. Or motivate yourself. Whatever has to be done it's always your choice.
In motivating people you've got to engage their minds and their hearts. I motivate people I hope by example - and perhaps by excitement by having productive ideas to make others feel involved.
Family involvement is a valuable thing and playing together actively can be the '90s version of it. Instead of just watching you can do it together something we don't spend enough time on. We can motivate and excite each other about fitness.
Leaders must be close enough to relate to others but far enough ahead to motivate them.