At what point should I stop exercising during pregnancy?

i still do my boxing & weight lifting. but the main point is, to know your body limit. dont over doing it. dont lift weight too heavy. cut the reps in half and the weight's too. depends on what your body says. stop when you reach the limit. before this i can do 1-2hours 1st trimester cant do anything. 2nd trimester i can do 1 hour. now im in 3rd, 30minutes and im out of breath hahaha