If you want to stay mentally fit in old age, it is best to look for stimulating activities. Which are they? It almost doesn’t matter. The main thing is that they meet one condition.
The plumber was there the other day to service the heating and to reveal the secret of a fulfilled old age. Mr. Müller comes by once a year and makes sure that the gas boiler and the other building services equipment in the basement continue to function trouble-free for as long as possible. The tall, gaunt craftsman exudes a calming composure. He never seems stressed or hectic, although he is always running back and forth between the basement and the car and, like any tradesman, is likely to be stressed and hectic given the workload.