I'm currently taking 40 mg of Prozac. From your experience, what is the dosing that is optimal for an adult male to decrease depression and increase motivation?

I've been on this medicine for four weeks now and every day after taking it my head becomes fuzzy and my body becomes heavy and slow. I know this is a side effect but I thought this would decrease after four weeks.

Can I add something for motivation (I can't take Wellbutrin)? If I make a change, do you have any recommendations for meds that increase motivation? It's my biggest challenge with depression!

Many thanks!