I probably did my first ritual at around 19 - I had been reading up on Wicca for about 6 or 8 months by that point... there was something refreshing about completing it, I remember, it was so cool. I had done a basic cleansing ritual in my bedroom, surrounding myself with a circle of pebbles & crystals, and did the whole candle/incense/salt/water schtick - very nice.
My first ritual felt great. It was a full moon ritual I think. I really connected with the gods and divinity and I felt so relaxed, happy and empowered.
I felt the same as everything mentioned here. it's like trying to explain love, it's hard to explain that feeling you get.
I just love the energy I get from any ritual, whether it's just casting circle for the sake of doing it, or if it's for a holiday, it's just so positive and refreshing...