Fernando Alonso considered quitting Formula One at the end of last season to pursue his Triple Crown dream, but decided he could not leave on a disappointing note.
McLaren have been beset by engine and reliability issues in recent years, leading to them switching suppliers from Honda to Renault for the upcoming season, and Alonso chalked up just 17 points.
The two-time F1 world champion skipped last year's Monaco Grand Prix in order to race the Indy 500.
That experience has whetted Alonso's appetite to add the Indy 500 and Le Mans 24 Hours to his Monaco Grand Prix wins – and complete motorsport's unofficial Triple Crown – but he opted to remain in F1 for the time being.
Speaking to F1 Racing, he said: "Yes, I did think about the possibility of changing series and stopping Formula One.
"After I did the Indy 500 last year, when I came back there were a couple of races in Austria, Silverstone, when I thought, 'maybe next year I could try a different series; I could do full commitment to the Triple Crown and do Indy and Le Mans and maybe that's the best thing'.
"But I felt it was not the time for me to step out - not right now, not after these results, not with this feeling.
"I knew I would regret it for the rest of my life and that I would have this bad taste for the rest of my racing career.
"So definitely I still want to succeed. There is unfinished business for me and McLaren together.
"And I think this year is the time all these things will change. I feel pretty sure about that."
Alonso has committed to the full season of the World Endurance Championship, in which he will race twice at Le Mans.
|Brown absent from Steelers facility on Monday due to ´personal matter´|
|Toronto´s Bussey given eight-match biting ban|
|Barcelona 4 PSV 0: Marvellous Messi lights up Camp Nou|
|Inter 2 Tottenham 1: Icardi, Vecino complete dramatic late turnaround|
|Allegri, Chiellini defend Costa over spitting ban|
|Firmino only fit enough for bench duty|
|Kovac applauds Sanches ahead of Benfica homecoming|
|Tomlin confirms Steelers WR Brown was absent from facility on Monday|
|Mourinho tells United to follow Federer´s lead amid Young Boys pitch concerns|
|Costa banned for four Serie A matches for spitting|
|PGA Tour announces changes to FedEx Cup Playoffs format|
|Rashford to start against Young Boys, Mourinho confirms|
|Ryder Cup heading to Congressional in 2036|
|I never listen to stupid things - De Gea unconcerned by criticism|
|Aguero trains as Mendy sits out Man City session|
|Lampard fined after accepting improper conduct charge|
|Serie B suspended after Pro Vercelli win appeal|
|Mitchell returns to England as defence coach|
|Brady completes Cornet upset in Guangzhou|
|Lopetegui giving no guarantees to ´fighter´ Navas|
|Di Francesco denies racially abusing Costa|
|Saunders apologises for ´sickening´ online video|
|Tianjin Quanjian 0 Kashima Antlers 3 (0-5 agg): Semi-final spot booked in resounding fashion|
|Madrid cannot live on Ronaldo´s glories, warns Ramos|
|Real Madrid are Champions League favourites, insists Man City coach Arteta|
|Stokes & Hales charged with bringing game into disrepute|
|Stephens slips to Vekic defeat in Tokyo|
|Simeone should teach Griezmann values - Ramos questions Ballon d´Or ambition|
|Arteta ready to step into Guardiola´s shoes after missing out on Arsenal job|
|Naive or scheming - Ozil´s agent slams Kroos, Neuer and Muller|
|Bolton´s Darby forced to retire after Motor Neurone Disease diagnosis|
|Root vows dressing support for Moeen over Ashes abuse claims|
|Madrid more dangerous without Ronaldo - Dani Alves|
|Federer fires ominous Djokovic warning to rivals|
|Arsenal confirm Gazidis departure to Milan|
|Man´s best friend? D´Arcy Short ruled out by dog bite|
|Salah has strong bond with ´friend´ Klopp|
|Mistakes were made in Serena´s US Open row - Federer|
|Burgess wants ´truth to come out´ over lewd video allegations|
|Injury brings premature end to Sharapova´s season|
|The next one´s mine - Griezmann underlines Champions League desire|
|A novice coach and a solar-powered stadium – who are Champions League debutants Young Boys?|
|Free-scoring Liverpool and PSG do battle, Kane eyes elite club - Champions League in Opta numbers|
|Braves fall to Cardinals, still move closer to clinching NL East|
|Mack leads Bears past Seahawks|
|Maradona makes winning start in Mexico|
|Barcelona captaincy has changed Messi, says Bartomeu|
|Lithuania qualify for FIBA World Cup after double-overtime win|
|Yelich makes history with another cycle|
|Silva: PSG, Liverpool have world´s two best attacks|
|It´s like a cow seeing a train – Pochettino uses unusual analogy to talk experience|
|Brady discusses Patriots´ trade for Gordon|
|Bills coach McDermott hasn´t spoken to Davis, says he ´didn´t feel a need´|
|Coutinho can´t explain Barcelona´s Champions League struggles|
|Henderson: Run to final can inspire Liverpool in Champions League|
|Eriksen: Everyone expects Kane to score a hat-trick every game|
|Gruden doesn´t regret decision to trade Mack|
|West Ham confirm Wilshere ankle surgery|
|Hughton hails Murray´s cool head as Brighton fight back again|
|It´s not good enough - Hojbjerg blasts Southampton|
|Patriots sign Josh Gordon from Browns|
|Southampton 2 Brighton and Hove Albion 2: Murray denies Saints after Hojbjerg howitzer|
|Wawrinka ready for Khachanov after battling past Bedene|
|Lozano: Joining Barcelona would be a dream|
|Players can fight for Messi´s shirt if they win, says Van Bommel|
|Kaymer tips Europe for Ryder Cup glory|
|Neymar to face Liverpool, confirms PSG´s Tuchel|
|Jardim backs Ronaldo to beat Griezmann in Ballon d´Or battle|
|Atletico will grow through hard work, says Simeone|
|Sorry Sri Lanka crash out of Asia Cup|