Born and raised in the city of Christchurch on New Zealand's South Island, Lentjes was educated at St Bede's College in his hometown where he won a Crusaders secondary schools title in 2008. After leaving high school, he made his way through the rugby structures, being a member of their wider training group in 2013 as well as playing for the Knights development team. He played club rugby in Canterbury with the University club, however, owing to a lack of opportunities to make the province's star-studded ITM Cup side, he headed south to Dunedin and began playing club rugby there for Taieri. He holds a university degree in geology and geography and worked as a lab technician for Fulton Hogan prior to his rugby career taking off.
Senior career
His move to Dunedin quickly paid off and after one season in club rugby, he made the Otago squad for the 2014 ITM Cup and went on to play eight games in his debut season, scoring one try. Injuries restricted him to just 6 appearances in 2015, but in that time he managed to score 5 tries which helped his side reach the Championship semi-finals before they were well beaten by. He was back to full fitness in 2016, featuring in 10 of Otago's 12 matches during a season which saw them finish 1st on the championship log and reach the play off final before being surprisingly defeated at home by.
Super Rugby
Following a string of injuries, Lentjes was called into the squad midway through the 2015 Super Rugby season, making his debut in a 39-21 victory over the Stormers on March 28. He remained with the squad for the rest of the season and played in both the semi-final win over the and the 21-14 defeat of the in the final which helped the Highlanders lift the Super Rugby title for the first time in their history. He was subsequently promoted to the Highlanders full squad for 2016, however the form of fellow loose forwards Shane Christie, Gareth Evans and Dan Pryor restricted him to the role of bit part player and he could make only 4 appearances as his franchise failed to hold on to their Super Rugby crown, going down to the in Johannesburg in the semi-finals. Despite his lack of game time the previous year, new Highlanders head-coach Tony Brown, who had worked with Lentjes at provincial level, opted to retain him in the squad for the 2017 season. New coach in 2018, Aaron Mauger made Lentjes a starting player and after 36 games for the super rugby side was named as captain of the Highlanders for the 2020 season.
