If you experience sudden very high spirits, possibly even a feeling of lightness, you are feeling great elation.
Elation is more than mere happiness — it is extreme, exhilarating joy. It has a sense of rising or expanding, even to the point of light-headedness. To help remember it, think of the (unrelated) word inflation, which has a similar sound. When you inflate a tire, you pump it up. When you are filled with elation, you are also, in a sense, "pumped up."