If high-stress Tokyo is getting to you, head to Kanagawa. There are plenty of outdoor activities and smaller cities to help you relax.
The port city of Yokohama has an amazing Chinatown (with spectacular food). Enoshima has a popular beach for hot summer days. If you go on any of Kanagawa's many hiking trails, you should visit the famous foot onsen in Yugawara afterward.
Whether you're a country mouse or a city mouse, Kanagawa will have something for you.