[1] It was only natural then that the younger Lastimosa started playing basketball at the young age of five in their family's residence in the city of Cagayan de Oro.
[2] He then joined the varsity team of Xavier University - Ateneo de Cagayan during his high school years, where he quickly became a subject of interest in the local basketball scene.
[1] It was during his stint at the Jesuit Athletic Meet in CDO first got the eyes of the scouts for his talent on the hard court.
[1] He was later then recruited by the Ateneo Blue Eagles Glory Be Team but was later released due to academic reasons.
[8] CSB ended the first round of eliminations with a win over the Perpetual Help Altas in which he scored 21 points.
[18] Lastimosa started CSB's Season 88 campaign with a win by scoring 10 points in the fourth quarter.
[23] In his professional debut, during the final moments of Barako Bull’s 2013–14 PBA Philippine Cup game against Air21, he was hit right in the face by Wynne Arboleda shortly after stripping the ball off the veteran Express guard.
[25] He had 11 points in a loss to the Alaska Aces, which gave Barako a record of 5–9 and with a higher quotient, the sixth seed.
[33] On July 2, 2015, Lastimosa was traded by the Barako Bull Energy to Blackwater Elite in exchange for Brian Heruela.
[34] Lastimosa's arrival at Blackwater earned him more minutes, owing to lack of pure scorers in the team.
In a 2015–16 Philippine Cup game against Meralco, he scored 11 points, 3 rebounds, an assist, and a steal off the bench and also made the game-winning floater.
[38] He helped Blackwater get into the quarterfinals for the first time in franchise history with 14 points in a win over the Mahindra Enforcer.
[41] Lastimosa started the Commissioner's Cup with a career-high 39 points on 4-of-7 threes and went 9-of-10 from the free throw line and also collected 4 rebounds and 4 assists as a starter.
[43] After the game, his coach, Leo Isaac, made comments in the team dugout that Lastimosa missed the free throw on purpose.
[46] Despite Blackwater not making the playoffs, he was a candidate to win Best Player of the Conference with averages of 21.2 points, 3.7 rebounds, and 2.5 assists per game, but lost to Calvin Abueva.
[52] On October 26, 2016, Lastimosa was traded by the Blackwater Elite to the NLEX Road Warriors in exchange for James Forrester and a 2016 2nd round pick.
[58] Their losing continued in the Commissioner's Cup, as they started with a loss to Rain or Shine in which he scored 15 points.
[60] In the Governors' Cup, he helped get NLEX its second straight win of the conference with 13 points, all in the first quarter.
[74] Manila got into second place in the standings with a win over the Bacolod Master Sardines in which he had 22 points and five steals.
[79] In Game 1 of their semis against the Makati Super Crunch, he made a clutch three-pointer and two free throws as he finished with 25 points, six assists, and three rebounds to get the win.
[84] Clarin started the season 5–0 with a win over the Kapatagan Buffalo Braves in which he made 22 points and six triples.
[86] They ended the eliminations at 7-1, good for the second seed, with their only loss coming against the Basilan Peace Riders.
[90] In a win over the GenSan Warriors, he had an all-around stat line of 14 points, two rebounds, four assists and a steal in under 23 minutes of play while also finishing with a team-high plus-18.
[91] He then led with 14 points on 6-of-16 shooting along with five assists, two rebounds, and a steal over the Imus Buracai de Laya.
[97] He was able to lead Pasig into the divisional semis by defeating Quezon City with 24 points, four rebounds, and two steals.