I 'think' I remember how I used to warm various things before I had a microwave.... but now I would hate to try.

I could warm tea and soup in a saucepan...etc... but I now use cloth bags filled with rice to warm my bed in Winter, and those require a microwave.

I pre-heat in a MW all sorts of things before toasting or baking them...

I 'could' do without a TV or phone or car, too....but.....