I can still remember my father and I going outside with a hammer and cracking nuts on the driveway. It was fun to do this as a child, but not so fun when trying to add fresh nuts to a cake or brownies.
When chopping nuts, they are actually easier to chop when they are warm. The meat will be more pliable and you will not have to chase pieces down all over the kitchen.
To warm the nuts, place them in the microwave and cook on high for a minute or so, mix with your hands and see if more time is needed.
After the first minute, only microwave in increments of 30 seconds. You don^D>'t want them so hot that you can^D>'t handle them and when they cool off they may be a bit crunchier.
You can also heat them in the oven by baking for about 5 minutes at 325º.