But I have to admit it's not the first time it's been said to me, so I've tried to think what other people see in me that I know is not true. My conclusion is that it's because outsiders only see the things I achieve/do - the novels, short stories, teaching, blog, Twitter etc. What they don't see is all the faffing around that I tend to do in the privacy of my own home.
We can't do everything. A high achiever such as, for example, Barrack Obama is busy holding international meetings with heads of state, but he's missing out on other things - wasting time on a sunny day with a couple of mates out in the garden with a glass (or two) of wine, for example, or watching The Shawshank Redemption for the sixth time. Now, you might prioritise Mr Obama's occupations over mine, and his are undoubted more significant than mine, but I get more enjoyment from revisiting a favourite film than I would from any amount of high level meetings with heads of state.
It makes no difference how clever or focussed or anything we are, we can't do everything. If we choose to do X, we can't do Y. All we can choose is what we put high on the list. I put writing and reading and teaching writing high on my list. I put going to the cinema and art galleries and being with family and friends even higher. Everything else is, frankly, an also ran.
I don't have any other hobbies. I don't sing in a choir, for example, or play sport. I don't cook, except for special occasions. I do minimal housework - my domestic standards are low, I'm not interested in immaculate or perfect. I don't watch much television. My children have grown up so I'm not bound by things like the school run.
So, yes, I do lots of writing related things, because that's what I prioritise. My priorities might not be yours - I once tweeted that I hadn't ironed anything in years, and someone tweeted back, how sluttish. That's her opinion. Mine is, ironed clothes don't make you a better writer (or a nicer person).
If you don't have time to write, it's nothing to do with being a good time-manager, and everything to do with what you're choosing to prioritise. If you want to write, you will. Make it your priority, and it will happen.