I coach a lot of different people.
And most of them experience overload, overwhelm or basic stress to varying levels in their life.
I have also found that people have quite a varied capacity to handle stress in their lives. Some can handle more, for longer, and some for less.
But this what I have found to be common. Most people overestimate what they can achieve in the short term (less than 1 year), and under estimate what they can do in the long term (3+ years).
It seems that most of us have a pretty ineffective crystal ball.