Some recent sketches, made on my iPhone 6s Plus, using just my finger, no stylus, and the app SketchTime. Try it, it's great fun, and you can playback the drawing in progress.
It's nice to take a break from more finished work from time to time, and just follow a simple line as it explores the forms that present themselves.
I find the most satisfying are, like these three backpackers, a minimum of line enclosing a maximum of space and gesture:
Now go try it! Let your line suggest, rather than define the subject, and just enjoy. Wait a couple of weeks, then go back and look at them with fresh eyes. You will be amazed at the amount of memory and suggestion packed into such a simple sketch!
I'm pretty sure SketchTime is also available for Android users, too.