When I read about the past tense I often see sentences such as,
The imperfect tense is used for descriptions of characteristics, feelings, and conditions in the past.
This confuses me when thinking about the preterite as being complete and the imperfect as not being complete. I'm confused because I feel as though there is a preterite counterpart. For example.
Me sentía feliz con mi novia. I felt happy with my girlfriend (maybe I still do maybe I don't anymore)
Me sentí feliz con mi novia. I felt happy with my girlfriend (but not anymore)
Estaba cansado. He was tired. (he may or may not be tired now)
Estuvo cansado. He was tired. (he is no longer tired now)
El atleta era fuerte. The athlete was strong. (maybe he still is today)
El atleta fue fuerte. The athlete was strong. (He isn't strong anymore)
The only time I can envision there not being a preterite counterpart is in an example such as,
El atleta era alto y fuerte. The athlete was tall and strong.
where "fue alto" wouldn't make sense.
So, my question is, is this statement true or can I use the preterite?