Painting relaxes me. Painting is also a spiritual journey of discovery for me. It can also be about technical mastery. I moved from watercolour painting to oil and now to egg tempera painting.
Only on a well prestressed sheet of watercolour paper can you work well and without puddles. Handling wet glue paper when mounting watercolour sheets is not easy - but I personally find such preparatory work very relaxing. Since I usually work on my paintings over a period of 1-3 months, it is very important that they always remain flat on the painting board over the entire period of working.