upbeat

An unaccented beat at the start of a musical phrase.

“The conductor said: I give you three beats for nothing and then you come in on the upbeat.”

Having a fast pace, tempo, or beat.

“The notes are easy, but it's an upbeat tune and should be played fairly quickly.”

Having a positive, lively, or perky tone, attitude, etc.

“He sounded upbeat when I talked to him.”