Here are a couple images where I have felt free while being stretched:
So, what am I trying to say? For me, at this point of my photographic journey, limiting myself with lenses can bread creativity. This can be with one prime, or one zoom, or some combo that intentionally limits me so that I will NOT be allowed to capture every single photo I see, but it forces me to think. This may be different for me later in life and it may be different for you now...but try limiting yourself in some way if you want to stretch yourself.