Remember distance running is a time aged process. It does not happen over night and more often than not it is what you were doing two years ago in training that results in the benefits that you get from racing well now.
As we get older we tend to try and cram things too fast. Hold back and just use common sense and over time and mileage, your results will improve as you get stronger and smarted. It takes time to learn your body. Running is not just a physical activity. It is also a mental one.
Plan your journey and start now.