I've cultivated a niche expertise that I translate well to a wide range of communities, but when asked politely I tend to give my time and even tangible goods away for free.
Now, I'm actively trying to change that. I'm getting married next year and am very excited to have a family in the relatively near future, so I'm paying off debts, I re-entered the workforce at a decent salary, and have been trying to train myself to be comfortable asking people for money in exchange for my time & expertise.
It has been harder than you might imagine, but I'm making progress. Being able to externalize the need to earn money via the idea of a future family has helped me, but I remain very uncomfortable asking and often find myself under-reporting hours spent, transportation costs, etc.
If I could just produce content, conduct research, give workshops & lectures & have someone else handle the money, I would be in heaven, but the few people I've spoken to about it, despite initial enthusiasm, have never followed through. Considering my own disposition, I obviously don't blame them at all :)
I read your comments here and then I saw it. I think it is a sign :)
Seriously, I am not sure this aproach will help you. It looks like to me that it is more about "why do it" than "how to do it". I think what you should do is put yourself in a position where will just assume you will charge for it, so you don't have to say "oh, I would like you to pay for that".
But that wouldn't help with you refusing to charge for long hours. But you may consider a transparent aproach for it. Why not sending an email asking your clients if they feel confortable with you charging some extra hours. If they complain, you don't charge, but I guess some may accept it and even enjoy if they are rewarding a good job. This way it is no more a binary "I don't charge and they never know/I charge and they don't like it". There is a dialogue about that may substitute any confrontation.
And I also appreciate your thoughts. Thank you.
Best of luck to you :)
If anyone on HN wants to start a speakers agency for tech/security folk, I'd be first in line to sign up :)