Yes, congrats on the hat!
I, too, remember how badly my arms and hands ached the first week or so that I knit. It does get better, but if you are one who tends toward tendonitis (no pun intended
), be careful to stop and flex your arm muscles every few minutes or so. Also, the same goes true if you suffer from carpal tunnel. In fact, knitting can lead
to either of those conditions (as can any repetetive movement action), so it is important to regularly stretch your arms and flex the muscles in both your hands and arms.