Headwinds are psychologically tough, you go slower than usual with the same effort. You just have to downshift, learn to accept going slower, and try to not let it get you down. Easier said than done.

When starting out I wouldn't focus on time and speed so much, just learn how to get to and maintain a moderate level of pain and physical stress and learn about your body on a bike. When things get tough try to frame it as a learning experience (not a suffering experience).

And make no mistake: it often takes discipline to ride to work when there's a perfectly good car sitting there.