I have two quotes for you:
"Painting is just another way of keeping a diary." (Pablo Picasso)
"Once drinking deep of that divinest anguish, ... How could I seek the empty world again?" (Emily Bronte)
What is it about art and suffering that seems to make them such comfortable bedfellows? For me there is a definite relationship between my emotional state and my productivity as an artist. I have discovered that two emotions drive me to paint in particular ... love, and sorrow.
I have had my share of both. Love started me painting in earnest; inspired me and sustains my ongoing activity. Sorrow DRIVES me to paint. Without a canvas to drain that ever filling well I am sure I would have killed myself a long time ago. Some people go to counselling, I head to my studio.
And personal opinion ... the greater the love, the greater the anguish, the better the work. My art IS a diary. Granted, probably only I can read it, but there is not a painting I have done that I can't look at and not know exactly what I was feeling, thinking and going through at the time.
See if you can work it out from this obvious one. If you get this right, I'll graduate you to a zebra ... that'll keep you guessing! ;o)
... and seeing as I am in a quoting mood, I'll leave you with this.
"Every artist dips his brush in his own soul, and paints his own nature into his pictures."(Henry Ward Beecher)