The influences we choose to have on our life can have a really major impact. At worst, stuff like addiction can happen, but even minor influences can have major impact.
Continuing on with the slave analogy (which is basically servant in Bible times rather than the abusive ones of US history), Paul talked about how those who are slaves to sin "were free in regard to righteousness" (6:20). Not only does sinning not make one righteous, but some people want to do sin just because it is bad! However, it doesn't end well. Paul rhetorically asks the fruit of the things "which [they] are now ashamed" (6:21). Often times, sin leads to regret for doing past actions because sin wrecks lives. In fact, "the end of those things is death" (6:21).
In contrast, the Romans later became slaves of God and "have [their] fruit to holiness, and the end, everlasting life" (6:22). The Greek word for "holiness" (Strong 38) has also been used to refer to "sanctification", and some translations like NET use that wording. Basically, the Roman Christians (and by extension anyone who decides to not only believe in Jesus but also commit to Jesus) are now set apart and growing towards maturity, especially considering the growth in character along the way. And as usual, these Christians also get everlasting life in the end.
Paul closes off with a brief saying -- "the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord" (6:23). God saved us and provided us a way to not wreck our lives, so why wreck our lives when we can grow in character and into maturity?