I'm a student at a reasonably prestigious, but not top, graduate program in mathematics. I'm happy here- I really like the professors in my research group, and I feel like I'm a pretty good fit for the program. I have a fantastic supervisor, and many of the other professors in the department like and respect me.
But sometimes, I really worry about my future in academia. I feel like I'm doing pretty well compared to my peers, but I'm just afraid that given the job situation I'm not going to be able to get a good postdoc, and ultimately not a good research position, because I'm not at a top program. Given that the people in my research group are well-regarded and a great fit for me, how much will the fact that I'm not at a top program affect my chances of getting a good postdoc in the future?