I've been planning like mad for my PCT thru-hike this spring and summer. Here's what I'm concerned about right now, at the moment, etc.
Cold weather: I generally don't hike much in the cold weather--if it's around freezing or below, I stay home. That's not to say I haven't hiked quite a bit on snow, but it's generally been in mid-summer. Yes, that sounds odd, but snow in the Sierras lingers in the high elevations until late June to mid July, depending on how much falls during the winter. I'm just not sure how much clothing I'll need. I think I'll be fine with a baselayer, midlayer shirt, a down jacket, and rain jacket. Maybe fleece? And for pants, leggings and my zip-off pants. I'll find out more next week when I'm camping outside of Lake Tahoe.
Food: Tricky. I was nicknamed "the airfern" on Sierra backpacking trips with the Scouts when I was a teenager... because I just didn't eat much. (I also weighed forty pounds less than I do now!) I've never enjoyed cooking, but do like hot soups and cocoa and pasta-y things when backpacking. I'll continue to worry about this for awhile.
Sierras resupply. There's not a lot of places to easily hop off the trail. My Sierra plans now start at Kennedy Meadows (mile 702, west of Ridgecrest and 395), then I'll go for six days and pop out the easy pass to Onion Valley and Independence for a night. Then several more days and then to Mammoth for two nights. Tuolumne Meadows is a small resupply, though it'll be mid-June. After that, it's 10 to 12 days walk to South Lake Tahoe. That section is problematic.
Timing. I wonder how far I'll get, but looking at things I'll be getting to Canada the first week of September. That's good timing (particularly in the North Cascades, when weather can close in from mid-September on), but I'll worry I'll pressure myself into trying to finish too quickly, and I won't have time to stop and enjoy the scenery along the way. I don't really want to feel rushed, but I really do want to complete the PCT.