40-60 mh/s isn't worth mining for especially you'll kill your GPU easily in a couple of months.
I did mine for like 6 months on my laptop, some Radeon 5xxxM (NB: now, about 9 months later, it still works fine). Only reason I stopped is because with the dust accumulating I was getting worried about the increase in temperature (dry air wasn't enough to clean properly, apparently). Just check your GPU specs and make sure your temperature remains in a decent zone. For me I felt it was okay as long as it remained <90°C. Underclocking the memory (a lot, increases performance a bit) and optionally the GPU (a bit, decreases performance proportionally) can help control temperature, too.
But yeah, you won't get much out of such a hashrate anyway.