Well, in search for martial efficacy, the practice is very hard. But as a DO (way) everyone can practice his/her way. As a matter of fact, Aikido has the highest rate of female and elder participants, because strenght is never required. Strong persons are continually urged NOT to use strenght.
Of course hearing that even Tai Chi puts a toll on you, that is discouraging a bit... Yet, you may approach an Aikido Dojo, and try.
As for hearing explanations, the Sensei is supposed to never speak, only demonstrate the tecniques. The Sensei will speak of course (we are not ancient japanese) but it is not needed to understand, you can only watch and imitate. I tell you that once I practiced in Germany. Only german was spoken on the tatami, but I could work nevertheless.