( ( The ( second ( preventive measure ) ) ) ( ( would ( ( ( be ( that ( of ( moderating activity ) ) ) ) , ) ( so ( that ( ( ( those individual ) ( who ( do ( in ( fact ( smoke cigarettes ) ) ) ) ) ) ( would ( have ( ( available substances ) ( that ( could ( ( ( ( ( moderate , ) decrease ) and ) hopefully ) ( cessate ( their behaviour ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ second) (NN preventive) (NN measure)) (VP (MD would) (VP (VB be) (NP (NP (DT that)) (PP (IN of) (S (VP (VBG moderating) (NP (NN activity)))))) (, ,) (SBAR (RB so) (IN that) (S (NP (NP (DT those) (NN individual)) (SBAR (WHNP (WP who)) (S (VP (VBP do) (PP (IN in) (NP (NN fact) (NN smoke) (NNS cigarettes))))))) (VP (MD would) (VP (VB have) (NP (NP (JJ available) (NNS substances)) (SBAR (WHNP (WDT that)) (S (VP (MD could) (VP (VP (VB moderate)) (, ,) (VP (VB decrease)) (CC and) (ADVP (RB hopefully)) (VP (VB cessate) (NP (PRP$ their) (NN behaviour)))))))))))))) (. .)))
The second preventive measure would be that of moderating activity, so that those individual who do in fact smoke cigarettes would have available substances that could moderate, decrease and hopefully cessate their behaviour.
(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.