I love climbing even though I'm in no way built for it. Sure, there are times when I've had enough and choose a different route round a particular climb, but generally I've got now problem.
IMO it's one of my fitness indicators, especially when I climb a ba5stard hill and need only a couple of seconds recovery before sticking it in a bigger cog and speeding off.
I think it stems back to my teenage road-riding days when I'd spend 8hrs in the saddle with a couple of whippets who were into hills. We'd go all over Hants, Surrey and Sussex and I never once got off an pushed. Hence I always summon up those memories when the going gets tough. Although in MTBing there are various climbs that either catch you out because they're just too steep or technical, especially in certain conditions, etc.
One thing I find weird is what I call thermals and anti-thermals.
– Thermals: Some stretches of road of trail can go uphill quite steep but I always feel like I'm being pushed up them.
– Anti-thermals: Other stretches can be relatively flat yet seem to suck every ounce of energy to get "up" them.