I enjoy my job, credit risk for an investment bank. I don't live for Friday nor dread Monday. It's mentally stimulating and provides a descent mix of stress and excitement to keep me on my toes (yeah, I get excited over working in excel, a rare quality!). An average day is 10hrs, before 9 to 6.30ish, including an hour for lunch and shorter breaks to chat with those around me.
Having said this, no, it's not perfect, but it allows me to have a healthy personal life (which now happens to be filled with training).
However, the job is deal flow based, so when there are a lot of deals or urgent ones, hours-per-day easily exceed 12 and sometimes include weekends. While this amount of work and my training can co-habitate over short periods (maybe a week?) it's not sustainable.
So far this year, I've stuck to ten hour days max but business is picking up and quickly.
I've discussed Ironman training with my managers and they are understanding/ supportive. My direct manager is actually a marathon enthusiast which further helps my cause (we actually have the same marathon PB at 3.19).
No major conflicts so far, but as the training picks up in the Build and Peak phases the juggling act will really test my time management skills. More to come on this as both training and work-loads increase.