you would need simultaneously
1) high power (greater than many watts)
and
2) very close distance (perhaps 1 foot away or less)
If you are a few feet away, there will be minimal effect.
If you are using a commercial wireless lan unit, with its standard antenna, the power transmitted is much less than one watt, and it is transmitted in all directions, so even if it was on your desktop...the power absorbed by your body will be negligable.
About the only place you might have trouble is with a rooftop dish antenna beaming a signal to a far away receiver. If you stood directly in front of that focused beam for some time, you might have some trouble with cataracts in your eye, etc.