More Sweep Picking exercises.
This should keep you busy for a while
The only thing that I'll add to the exercise is this- After you get the ascending and descending exercises down, try to skip around a little bit. For example, in C major, you'd start with the C major arp and then skip the D minor arp and go to the E minor arp and then back to the D minor arp, the F major, then E minor again, then G major, and so on and so forth.
Bonus points for anyone who uploads a video demonstrating this exercise in the "Discussion Thread" below