Forcing motivation does not work. Not for your kid. Not for your spouse. Not for your parent, your best friend, or anyone else you love. You can want it badly, more than they do, more than anything. It still will not work unless they want it themselves.
That is a hard thing to accept, because helping is the part you can control. You can pay for the best coaching. You can buy the gym membership, book the sessions, stock the fridge with better food. You can send the articles, make the plan, clear every obstacle out of their way. All of that matters, but only after one condition is met: they have to want to be there.
If they do not, none of it works. Their effort is the ingredient that turns everything else into results. Effort comes only from the person doing the work.
When helping becomes pushing:
You see someone you love struggling with their health, their strength, their habits, and you want to fix it. So, you push by reminding them and signing them up for things. You tell yourself you are doing this for them!
But watch what happens on their end. They show up physically and check out mentally. They go through the motions, do the minimum, and begin to resent it, maybe even resent you. The thing you wanted to give them becomes one more source of pressure, and now the gym, the walk, and the meal plan are associated with obligation rather than progress.