What are the basic limits as the pregnancy progresses? Like weight lifting, or activities?

When I first found out I was pregnant, my doctor told me I could do whatever I did before pregnancy as long as I wasn't going over board or trying something new.

Example: If I lift 15 pounds repetitively for my job, that is fine, but don't start running 5ks if I am not a runner.

Now that I am in my 3rd trimester, I find myself easily tired or strained by my normal job or daily tasks. So if I feel strain, I stop and ask for help.

But is there some global limit I should be aware of? My husband doesn't want me lifting more than a gallon of milk and won't let me reach above my head at all. But for my job...that rule doesn't work.