Assalaamwa'alaikum

I just need some help regarding intentions. Ihave an OCD and waswas problem but with the help of allah (swt) I am overcoming the problem.
I just need to know how the intention is meant to be made. I know that it is supposed to be from the heart bit what does that mean. What I do is I think of every individual word in my head which I know is wrong because it takes me about 20 secs to do it while other people that just read salah I see them not even taking 5 secs. What I think of is, "O Allah Ta'ala I making my sunnah wudhu for you now" for example.
Please could someone just advise me on what to do here because with me OCD and waswas problems it sometimes takes me up to 5 mins to do

Jazakallah for your time