> Sure, thus the "find a trainer" suggestion

Not sure a trainer is a silver bullet. After 50, it gets increasingly harder to improve as we become more and more injury-prone and start developing chronic issues. Staying active and fit should be reachable for most, but high-intensity or competitive sports become a privilege for those with good genetics. Most of us switch to low-impact sports such as cycling, swimming, hiking, bodyweight training and so on...