Any way to log time automatically on work start?

[Arbak Martirosyan]

Title says it all. When user marks task as in progress/starts work, any way to start logging time without manual input? 

I've heard about Automated Log Work plugin but it seems that this is basic enough feature that you can do without plugins. 

Any way to do it with post-functions? There's a way to update remaining/original estimate on issue transition, but only with static value.