I've had both those types of thoughts (more an impulse in the first case.) The time I was having the biggest problem with wanting to crash my car, it turned out that I seemed to be reacting negatively to the oral contraceptives I was taking.

I was reading something unrelated the other day and happened on some material about people having an urge to crash their car into things that said it's an extremely common thing for people to experience. I had no idea. Maybe people don't tell other people? It's scary, because it's like a sort of urge to do but you don't want to do it at the same time.

When I have had the thoughts about not being able to imagine living past a certain age (usually a year or two into the future), that has usually been when I'm depressed. It seems to be very anxiety-related. When I feel that way, I feel like my life is so awful that the idea of it continuing for many more years panics me.

I don't know if that's how these things feel to you.

As far as contacting your therapist, I think you'd have to evaluate how much these thoughts are bothering you.

Some other things you could do are to look at your nutrition. (My opinion - my own anxiety level is very linked to how well I'm eating.) There are lots of books and web sites with info. about how to eat to help anxiety and depression.

Things like meditation, yoga, massage, and other calming things might be of help to you as well.

I was about to write that I hope you're able to get rid of these thoughts, then I remembered that one approach to dealing with thoughts like these is to just notice them and let them be. I find with myself that when I have thoughts like we're discussing, that they're a bit like little kids wanting attention - if I just notice that they're there but don't pay them much mind, they're quite likely to go away.

Having said that, if you find that the thoughts get to the point where they are causing you significant distress, then yes, I'd seek help from a therapist or psychiatrist.