Training after 40 is not a decision to stop chasing ambitious goals. It is a reason to make recovery, strength, sleep and load management part of the plan instead of treating them as optional extras.
What to keep
Keep easy mileage, long-run practice and the workouts that have worked for you. Fitness still responds to consistent aerobic work and purposeful intensity.
What to change
Leave more space between hard sessions when you need it, increase strength gradually, and pay attention to morning stiffness and lingering fatigue. A plan that looks slightly conservative on paper can produce better training over twelve weeks.
Set a useful goal
Use recent race results, current weekly volume, course profile and available recovery time. Choose a primary goal and a flexible effort-based backup so one hot day or poor night does not ruin the whole experience.