1. Experience (or lack thereof): It's a double edged sword, you may stop making any progress through paralysis-analysis. Progress is the best motivator and when you don't it starts affecting you in ways you will be surprised.
2. Cost of living: As you get older the cost of living only climbs up. You will be shouldering a lot of more responsibilities but biggest of all which I experience personally is associating dollar-cost with my time. You start valuing cost of money over cost of opportunity. If I am not making money that means I am loosing money.
3. Social pressure: We are social beings and when you see your friends moving ahead in life and you tend to remain where you are ( think first 1k days https://www.youtube.com/watch?v=L03vBkOKTrc), you need to have a certain kind of personality to be able to get through that period. Not vacationing, living a frugal life & compromising at every stage takes a toll on you personally. It starts affecting your mind in weird ways.
This is by no means a comprehensive list but it's my own experience & it's a constant battle especially when the chips are down.
EDIT to clear #1 speaking as an older developer.