prayatnaadyatamaanastu yogee samshuddhakilbishaha |
anekajanmasamsiddhastato yaati paraam gatim || 45 ||

For, that yogi who strives diligently, whose sins have been purified, perfected through many births, he then attains the supreme state.
prayatnaat : diligently
yatamaanaha : who strives
tu : for
yogi : yogi
samshuddha : have been purified
kilbishaha : sins
anekajanma : over many births
samsiddhaaha : perfected
tataha : then
yaati : attains
paraam : supreme
gatim : state
Shri Krishna spoke earlier about the unfulfilled meditator who, having born into a prosperous family, finds himself pushed towards the spiritual path. Here, Shri Krishna talks about what happens to that person if he strives diligently. Such a person, if he puts in diligent effort, acquires spiritual prowess over many lives, purifies his sins, and ultimately attains the ultimate state of liberation.
Now, the plight of someone born into a prosperous family, yet is being pulled towards spirituality, is extremely interesting. On one hand, his family wealth has the potential for generating further selfish desires. One the other hand, the push towards the spiritual path has the potential of taking him towards liberation. What will decide his fate in regards to which side he ends up on? It is nothing but his effort and his diligence.
Therefore, Shri Krishna encourages Arjuna to relentlessly pursue this path. Arjuna is born into one of the most illustrious families of his time. But through the knowledge that he is receiving from Shri Krishna, he has the option of pursuing the spiritual path, but only if he incorporates this teaching into his life.
How exactly should he incorporate it into his life? That is taken up next.