Yes, I find that's what I generally hear if I dare complain - 'oh, you're never bloody happy!'
I am, actually, more than happy in cooler weather. I don't know why people seem to equate disliking (for Britain) extremely hot weather with dislking ALL WEATHER.
Yes, those who hate the heat are lucky that we don't live in sweltering Africa. But I suspect that if we lived in sweltering Africa we would have acclimatised over many years, as opposed to the few weeks of relatively extremely hot weather we sometimes get here in Britain.
Also many people seem to forget that countries that are routinely much hotter than ours are far far more geared up for heat. Homes, shops, transport are all air-conditioned. There is more natural shade built-in to cities as protection for the hot summer months. People alter their days to work around the heat (eg in southern Spain where people rest inside in the hottest part of the day instead of going out bloody sunbathing like they do here) and stay out late to take advantage of the cooler nights.
I have a friend who comes from a country where summer is routinely 40 degrees. She says it's bliss, as when she visits she stays in her parents' cool, air-conditioned home, gets around on the cool, air-conditioned transport and hangs out in the cool, air-conditioned shopping malls. She's never hot when she's there, never over-heated, despite the temperature being much much hotter than here. Because her home country has a system in place that allows for normal life to continue in the hot weather.
Our country doesn't. And realtively speaking, the current temperature here is HOT. (28 in London, which feels hotter due to humidity and pollution).
It's spurious to say that we're lucky we don't live in a really hot country. The whole point is that we don't. So it's hard to adapt. And there are few modifications made to allow us to easily adapt.