Why is my power MOSFET heating up when on?
The only mistake is using the NFET as a high side switch when it should be a low side switch with Vs=0V then with Vgs>=10V you pull down the load cathode and series R from the supply with the drain.  

So transistors used as switches (FETs and BJT’s) are always inverting.  Vgs is chosen from the specs or as a rule of thumb Vgs>2.5 x Vt(max) the threshold of conduction, also known as Vgs(th).