"Olympic medal winner" is like a golden ticket in the fitness trainer industry. There's a lot of rich people who would be willing to pay over the odds to be trained by her.
Of course, she might want to stay well away from her past career for other reasons, whether it's boredom, self-consciousness, frustration or a strong desire to draw a line under it (FWIW I know an Olympic medallist who made plenty of money from endorsements and speaking engagements and could probably have had a media career but had absolutely no desire to do that or become a trainer/ambassador after his retirement, choosing to became a builder's apprentice instead, because he liked the idea of building stuff rather than because he needed the money)
So coaches I bet would only be making $20-30k per year. Barely a living wage these days, unless you live in Montana