Morning (aka all day) sickness + exercise...?

I'm 5 weeks pregnant and my morning sickness hasn't been too bad so far. It's a continuous nausea all day, but it's not like I can't function...except when I do any type of exercise. Today I was walking from my on-campus apartment to my class and I literally had to throw up in the bushes in that 5 minute walk - and it's like this every time I try to do any kind of walking. I know how valuable doing at least some exercise is, but that's when my "morning" sickness hits the worst! Anyone else have experiences like this? What do/did you do? I wanna keep active AND keep my food down...