Have confidence in your own ideas
If I took a very long break from my painting, or if the break was caused by a reason that still affects me, I return to my first love: drawing.
Drawing or sketching outdoors has a very purifying effect on me. I really see this as an effective method of meditation, as our mind wanders away as our eye and hand draw the subject before us. This brings me directly back into the mood of painting.
Drawing is my favorite medium. I've been drawing since I was very young, since the age of 3. I like the possibility of really working on a subject; details, shadows, contours. The drawing offers greater latitude to correct and modify the subject. We have more time, less pressure, less stress... more peace.
I think drawing centers me on myself, because I really go back to my artistic roots. Which is important in times of doubt or lack of motivation.
If you use a different technique, go back to the technique that is most familiar to you and, again, play around or focus on topics that you feel comfortable with. Simple and familiar topics to start with.