[Discussion] How to stay motivated when writing a series

Hi all, been (nearly) a month in the querying trenches with an MS I want to be the beginning of a mystery/crime series, but it's been so hard to bring myself to work on potential sequels when the current one hasn't yet got any agent interest. Obviously, I know it can take a year or longer to even get representation, and a month isn't very long so I really shouldn't panic, but I WANT to write these books - and then when I sit down to do it, I am just full of doubt.

Wondering if anybody has advice for how you keep the motivation to write those sequels when you have no idea if anyone will ever even read the first one?

Thanks in advance