If you don’t complete things you can’t claim them as done.
You can start all the projects you want but if you don’t finish them you’ve done nothing. If you’re working on a side project don’t move on to that new idea you’ve just had until you finish what you’re doing. Otherwise it’s incomplete.
If you’re going for a five mile run but only run four miles, it’s incomplete. You don’t get to tick it off your list of things to do. If you’re trying not to break the chain, you’ve failed, the task is incomplete and the chain is broken.
Don’t just start stuff, finish them.