The functions are many on our wrist-worn data collecting training tools. And in some ways, the putative cause for that post-training bliss might be the very data stored on that GPS/HRM device when uploaded to your training analysis app. Maybe you notched a PR, or simply logged 10,000 feet of vertical gain during that offseason ski tour. Or … you simply like pinpointing precisely where your heart rate spiked during that pre-Birkie time trial. Whatever...