Writing for Non-Fiction Genres

» Laurie Pawlik-Kienlen - waiting on publishers & agents

Help me I'm stuck! I have an agent and a publisher considering one book proposal, and a publisher who just needs to give me "some feedback and if we're on the same page I'll send a contract - there aren't enough hours in the day!" for another book idea. I've been waiting for a week on the first and four months on the second.
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Now what do I do? I don't feel like working on either book because I don't have contracts yet, and I don't want to put hours in without knowing if they'll want major changes --- or if they'll even end up buying them at all. I feel unmotivated and STUCK.
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Do I force myself to proceed on my book ideas, or just continue to twiddle my thumbs? (well, I write for Suite and others, and read lots about writing, and go to work. I'm not exactly just sitting around - but I am wasting valuable writing time). Do I proceed with the books or write other articles?