Recently moved and am settling into a new life with new routines. This threw off my bike commuting for much of the winter. But the last couple months I've been back in the saddle 3-5 days per week. Sometimes on my touring bike, sometimes on my gravel bike, sometimes on my cheater (electric) bike. I'm definitely out of practice, and some days I just don't have the stamina I think I do. Yesterday was one of those days. A slight headwind...that shouldn't have been a problem...felt like a problem.
I need more practice. The good news is I'm getting it regularly, so this problem should gradually correct itself.