Time and again I hear from prospective students how hard watercolor painting is.  Maybe it is because I have been painting with watercolors for so long that I believe it to be one of the easiest of media to be involved in for several reasons:  it is one of the least expensive, has the easiest clean up, it is portable, and when you get control of the medium, it is  physically effortless.  "When you get control of the medium", ok, that might be the difficult part, but not because it is labor intensive, but because you have to change your way of thinking about painting.  Most people (especially those who have mastered acrylics or oils),  tend to think of painting as an application activity, this is, one in which you physically take the brush and coat the paper with paint.  With watercolor it is less about heavily applying paint to the paper but more about guiding the paint on the paper.  It is hard to give up this control.  Because watercolor is so heavily based in water the paint almost "paints itself"  and your job is to guide it.  You need to step back and let the watercolor flow onto the paper.  You need to have a more gentle approach so that your painting does not become overworked and muddy.  If you work "heavy handed" where you apply pressure to the brush as it strokes across the paper you will actually lift off water and color from your painting.  

Another misnomer about watercolor painting is that you cannot fix your mistakes.   This sends prospective watercolor artists running to other media.  I have "fixed" countless errors.  I have even taken watercolor paintings out of their frames years after I painted them and  reworked them.  Once students learn that this can be done it gives them so much more confidence and motivation to continue with a medium that is so rewarding and fun!