I fill my water bottle up before I leave home and work. Plenty hot here in the desert.Aside from that, minimal planning. I bring a change of clothes into work and have a towel here too, so I can dry off if I've had a particularly sweaty ride. Every week I cycle the work clothes, so that takes some planning but not much. And I try to make sure I've got minimal repair tools (multi-tool, wrench, pump, etc.) in the event that I need them.