Students at a youth empowerment summit were urged Saturday by a celebrity speaker to say "yes" to making a positive impression. About 45 students from Simi Valley high schools participated in the second annual leadership program run by Simi Valley Rotary Clubs at Corriganville Park.Simi Sunrise Rotary Club member Dorina Timbol created the all-day free event."I worked in conjunction with Lora Sominsgaard, who was a great mentor of mine," Timbol said.