( ( State ( anti-tobacco activities ) ) ( ( ( ( ( ( decrease smoking ) ( by ( white youths ) ) ) , ) but ) ( have ( ( no ( significant effect ) ) ( on ( ( ( ( young blacks ) , ) particularly ) ( black males ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP State) (JJ anti-tobacco) (NNS activities)) (VP (VP (VBD decrease) (NP (NN smoking)) (PP (IN by) (NP (JJ white) (NNS youths)))) (, ,) (CC but) (VP (VBP have) (NP (NP (DT no) (JJ significant) (NN effect)) (PP (IN on) (NP (NP (JJ young) (NNS blacks)) (, ,) (RB particularly) (NP (JJ black) (NNS males))))))) (. .)))
State anti-tobacco activities decrease smoking by white youths, but have no significant effect on young blacks, particularly black males.
(ROOT (S (NP (NP (NN Smoking) (NN tobaccowould)) (ADJP (RBS most) (JJ likely))) (VP (VBP have) (NP (NP (DT a) (JJ negative) (NN impact)) (PP (IN on) (NP (NP (DT the) (NN ability)) (PP (IN of) (NP (DT an) (ADJP (JJ individual) (S (VP (TO to) (VP (VB succeed) (PP (IN at) (NP (JJ physical) (NNS activities))) (SBAR (IN because) (S (NP (PRP it)) (NP (PRP it)))))))) (NNP decreases) (NN stamina) (CC and) (JJ cardiovascular) (NN efficiency))))))) (. .)))
Smoking tobaccowould  most likely have a negative impact on the ability of an individual to succeed at physical activities because it it decreases stamina and cardiovascular efficiency.