Not sure why you are correlating the terms "stupid" and "dumber" with exercise.
Aerobic fitness has been shown to have significant correlation to executive function in the brain, which affects decision-making, mood, and the speed of information processing.
Weight training has not yet been shown to have significant cognitive effects, either positive or negative.
As a lifelong swimmer, I can also say from personal experience that my focus and motivation seriously benefit from maintaining a routine exercise program.
Your perceived lapses in cognitive function are are probably more behavioral; instead of standing around thinking and smoking, now you are spending that time engaged in both mind and body.
Aerobic fitness has been shown to have significant correlation to executive function in the brain, which affects decision-making, mood, and the speed of information processing.
Weight training has not yet been shown to have significant cognitive effects, either positive or negative.
As a lifelong swimmer, I can also say from personal experience that my focus and motivation seriously benefit from maintaining a routine exercise program.
Your perceived lapses in cognitive function are are probably more behavioral; instead of standing around thinking and smoking, now you are spending that time engaged in both mind and body.