Problems with an ILI

I'm having problems with an ILI and maybe wondered if you had any tips?

It's just the person is such energy sapper and every time i suggest something "yes, i can do this, it's doable" i get in response all the potential pitfalls which frankly i've already thought about so it's really pointless of them to mention, but it just still has a negative impact since it casts doom and gloom over my intended project.

Any tips how to 'immunize' myself from this? It's gotten bad since I tended to confide in them a lot for projects i'd wanted to do but now i'm seeing the negative effects of that and really wanted to avoid it if at all possible. My guess is that's their way of helping;

Any suggestions? Thanks.