Cyprian of Carthage is a fascinating man. Born around 200AD into a pagan family in North Africa, he became a Christian at age 46 and by age 48 was made the bishop of the church in Carthage. In his time, he suffered persecution in several waves, mobilised the church to social action in helping the victims of a plague, tackled some major pastoral and theological issues (e.g. should Christians who gave in to pagan pressure under persecution be allowed back into the church?) and was martyred at the age of 58. In his 12 years of being a Christian he had a huge positive impact, although we would not necessarily agree with all his theology.
The apostle Paul became a Christian in 35AD, but it was another 10 years before he started his first missionary journey. Over the next 20 years, he planted many churches and wrote around 30% of the New Testament before his martyrdom.
We may not have the impact of the above, but God calls each of us to have an enthusiasm for Him and His kingdom (eg Matthew 6v33, Philippians 3v8). What is the Lord calling you to? How great is my courage and what is it based on? A life given over to Him can have huge impact in a short space of time. By the way, there is no guarantee you will martyred!