Dig yourself a writing cave

A writing space is as important as writing time.

When you have a special place where you write (I have a very deep, very dark, very scary cave, for example), you tend to write there just because you're used to doing it there.

Also, your headspace becomes attuned to your physical space.

I'd say, develop a whole ritual around your writing so it puts you in the mood. Kind of like putting on workout clothes puts you in the mood of working out. The same principle applies here. Drink the same drink....