I have been doing WW for about 3 weeks now and want to start actively working out.

I don't know how to determine activity points for myself though. From what I read it is how much you perspire, light-heavy.

I don't perspire and never have and never will. Just a weird thing about me. I just get very overheated and have to know when to stop.

How should i calculate my points?

Here are some formulas that may help you calculate your exercise points:

Light Activity (you can feel it a bit but not too stressful):
Weight x Minutes x .000232 = Activity Points

Moderate Activity (you can feel your heart rate rise a bit and lightly perspite):
Weight x Minutes x .000327 = Activity Points

High Activity (heart rate rises and you break a good sweat):
Weight x Minutes x .0008077 = Activity Points

Hope this helps..

since you dont sweat...try calculating by judging your breathing.
light-can carry on a conversation with someone while working out
moderate-can talk or sing but its more difficult
intense- can not talk or sing while working out