Is 10,000 steps a day enough on its own, or am I missing something at 42?

Honest assessment: it covers a lot and it leaves one clear gap, and the gap gets more important at your age rather than less.

What walking covers well. General activity levels, cardiovascular health at a moderate level, mood, sleep, joint mobility, and the sheer benefit of not being sedentary — which is the largest single health difference of all, and you have already banked it.

What it does not cover. Resistance training. Muscle mass and bone density decline gradually from the thirties onward unless something loads them, and walking does not provide enough load to prevent that. It is not a small omission — muscle and bone are what keep people independent and unbroken decades later.

General activity guidelines from health bodies reflect this: they recommend aerobic activity and muscle-strengthening activity on at least two days a week, as separate items. You are comfortably meeting the first and not the second.

Worth knowing where the number came from, because it will stop you treating it as a target with special meaning.

Ten thousand steps was, by most accounts, a marketing figure attached to a step counter decades ago, chosen partly because the character for ten thousand looked like a walking person. It was not derived from research.

What the research since then suggests is that benefits accumulate well below ten thousand and continue past it with diminishing returns, and that the curve is steepest at the low end — the difference between two thousand and six thousand steps is far larger than between eight and twelve.

So you are comfortably in good territory, and there is no particular magic in the specific figure you are hitting.

The second gap worth mentioning is intensity.

Walking at a comfortable pace sits well below the intensity that improves cardiorespiratory fitness meaningfully in someone already accustomed to it. You get the health benefits of activity without much of a training effect on the heart and lungs.

Two cheap adjustments, neither of which requires a gym:

• Add hills or pace. A few segments of your existing walk done fast enough to make conversation difficult changes the stimulus substantially without adding time.
• Carry something. Walking with a loaded pack turns a walk into loaded exercise and does provide some of the missing resistance stimulus, particularly for the legs and trunk.

Both fit inside the habit you already have, which matters — you said sustainability is your priority, and it should be.

For the resistance part, the minimum effective version is smaller than people assume: two sessions a week, twenty to thirty minutes, covering a squat pattern, a push, a pull and something for the hips.

That can be done at home with no equipment initially and it addresses the gap almost entirely. Given you have already built a daily habit that has lasted months, adding two short sessions is a far easier proposition for you than it is for most people starting from nothing.