How can I take this calm feeling with me for the rest of the day?

Before standing up, form a clear idea about what you're going to do next. For example, are you going to the bathroom to brush your teeth, to the kitchen to make a cup of tea, or to pick up your keys before leaving the house? It's so easy to just jump up off the seat and lose the calm and spacious quality you've so carefully cultivated. So try to carry this awareness with you to the next activity.