Ebullient – overflowing with enthusiasm, high spirits, etc; showing much exuberance or exhilaration

“[Roosevelt’s] ebullient and joyful persona entranced voters.”

from the introduction to Lion in the White House, Aida D. Donald

“The colonel [Roosevelt] was probably the best-known politician in the country, having been a military hero and in public life since the age of twenty-three. His ebullient personality, varied talents, war record, and reputation as a reformer – although a not wholly successful one – in an age of acute conservatism made him a popular figure.”

Lion in the White House, Aida D. Donald