以下TED摘錄句之 ”what I noticed IS that…” 及”that’S what kept me …” 文法是否有問題?

But what I noticed "is" that after every sweat-inducing workout that I tried, I had this great mood boost and this great energy boost. 所述雖是我以前的經驗（noticed, tried, had都是過去發生的action verbs）。但主要動詞state verb的be動詞，用了「現在簡單式」，表示所述狀況是真實的。如果只是以前才如此，現在不一樣了，或是強調「當時」是這個狀況，才會用「簡單過去式」。
And that "is" what kept me going back to the gym. 理由同上。也是表示所述為真實的，所以用「現在簡單式」的is。
兩句的主要動詞都是be動詞。

what I noticed (is that)-------used at the beginning of a statement to emphasize what you are going to say
=what mattters is what I noticed
=what I noticed--n.cl.

that is (what kept me)
=used to introduce a clause about something that is known or certain--what to do/say/expect showed/kept.
=that is (what kept me)
=what I showed
=the thing which
=what kept me--adv.cl