Negative emotion

I’m having trouble accepting that 50% of my life will be spent in negative emotion. For me negative emotion means unhappiness. I think about whether I would be willing to spend half of my day being unhappy (and the other half happy). This just doesn’t sit well: why would I be ok being unhappy. I also think about the people I love spending half of their lives being unhappy and I struggle to be ok with this. I accept that of course you can’t (and don’t want) to be happy all the time but I keep tripping up over having 50% of your time spent in negative emotion.