I've been teaching for nearly 8 years now and started tri this year. Only done two sprints but now training for an Olympic and my first OW swim. I cycle to work one day a week 30 KM each way. I also try and go to a swim session at my local pool that is for the cost of any lane swim. I try to run a couple of times a week as well But this suffers as my bike and swim need the most work.
Fitting it in can get tough and it's a case of I do some of my best thinking when I'm on the bike or running. I've got into a routine so when I don't train I get grumpy and feel less productive at work.
Getting the balance is hard but your workload will never get less but you learn to work smarter. I'm a HOY and have a young family but you will find a way to fit it in I you really want it.
I'm another large runner. I've found that running on trails and off road has helped me to shake some of the niggles.
I tend to have an older pair of shoes for training and a newer pair for races same make and model. When training pair dies I buy a new pair to race in. I've found that I get more miles out of my NB 890 than any other shoes I've used.