For English Speakers - get rid of the progressive form.
Think of it. TO BE something is static. So, in a binary sense, you are something or not. If they, you are in the process of becoming, there is the sense of "busy with it" that the progressive tense speaks to.
Ek is moeg. (Present Tense/Hede)
Ek word* moeg. (I am getting tired.) Present Progressive
Ek sal moeg wees. (I will be tired.)
Ek sal moeg word. (I will be getting tired.) Future Progressive
Ek was moeg. (I was tired)
Ek het moeg geword. (I was getting tired.) Past Progressive.