Lerning something completely new – i.e. completely different from anything else you have learned so far – stimulates your brain to build new neuronal structures thus making your brain more flexible. This could be a totally unusual pattern of movement or a new job in completely different field of work, or learning a new foreign language or a training of your brain based on associative learning as practised on a daily routine basis by memory experts.

If your brain is limited by only guiding you through your accustomed daily routine, there will be just low activity in your braincells. So it is not necessary to build up new neuronal connections and the enormous potential of our 100 billion brain cells remains unused. What counts most is, constant discovery of new information and procedures. This will only happen, if you leave your "comfort-zone". That doesen't mean giving up all convenient, easy going habits, but it does mean to change some of them. Hapiness induced by achieving your goals after a period of consistent effort is maily attainable outsid this comfort zone.
My suggestion: Leave your comfort zone, take new challenges, accept failures, develop the potential of your brain. Lickily the necessity for constant learning stimulates growth of neuronal structures even with lazy people. By the way: each brain-cell has the ptential to form connections with 10.000 other brain-cells. This is a virtually unlimited potential! Are you using it or are you stuck in your comfort zone?