want to have hope, but need to be realistic

I have been married for 5 years and my husband is undiagnosed. I would really like to hear from some of you who have seen improvement or progress with your spouses ... I love my husband dearly and am committed to him forever. But I have been realizing lately that I no longer believe him when he says things like, "I am going to get fit." or "I am going to start practicing the guitar." etc etc. I feel like his goals are wonderful and he has great ideas but can't seem to make them stick longer than a week or so. I don't like the fact that I don't believe him anymore ...