Saitama has a training regime, which someone in real life replicated with great results. 100 push ups, 100 sit ups, 100 squats, 10 km run. Everyday. There's a second part to the training: if it's cold, don't turn on the heater, and if it's hot, don't turn on the AC or fan. The cold thing has been working for me so far. When it's cold, don't immediately wear another later. The heat part, I'm trying. There's a heat wave in Europe right now and it was 42 degrees Celsius yesterday? I let the fan turn instead of facing it and I can't afford an AC anyway. It seems every post on reddit and every conversation is about the heat. I am slowing getting irritated with the comments, just like how I get irritated by the comments during cold. I have low heat resistance and I've complained LESS this year. So, either buy an AC, plant some trees, shut up or be like Saitama.