Re: Hard to Stay in Seiza
If you have a specific injury that is aggravated by seiza, tell your sensei.
If you don't have a specific injury, but you find seiza painful and difficult, and your sensei wants you to sit in seiza, try some of the off-the-mat exercises to increase your tolerance.
I understand and agree with Takahashi Sensei's reasoning re: the possibility for injury, and why go there. At the same time, sitting in seiza is the only way to get over the discomfort of sitting in seiza, or being able to do it for longer periods of time. That doesn't mean that more is better, but on the other hand, I know people (without injuries) who always switch to sitting cross-legged at the first sign of discomfort, and I observe that as time goes by, they are not "able" to sit in seiza any longer than they were at the beginning. So, if being able to sit longer in seiza is a goal for you, I think that you will have to endure some discomfort as you build up your tolerance.