Blind Drawing and Mindfulness

One morning, I spent one and a half hours blind drawing. It was intensely relaxing, and left me with an inner glow that lasted for the entire day. I've had similar feelings before. Once when I was blind drawing from memory in Cornmarket, I felt an intense buzz as though I'd swallowed a chilli, followed by an intense calm.

Why? Would blind drawing be useful to those who teach mindfulness? I often feel relaxed after blind drawing, and I'd like to know why that is, but the episodes above were unusual. Whether or not there's any correlation with my ability at the time, it was very pleasant, and I'd like to know how to repeat it.