Renault-bound Daniel Ricciardo was struggling for motivation at Red Bull

SPA-FRANCORCHAMPS, Belgium -- Daniel Ricciardo says his decision to leave Red Bull for Renault comes down to a need for a fresh challenge in his career after 10 years affiliated with the energy drinks company's Formula One operation.

At Thursday's press conference ahead of this weekend's Belgian Grand Prix, Ricciardo faced the media for the first time since his shock announcement at the start of the summer break. Despite being flanked by Carlos Sainz and Pierre Gasly, who will also be moving teams, and Fernando Alonso, who also used the break to announce his decision to quit F1 at the end of 2019, Ricciardo was asked the majority of the questions.

Ricciardo, who won races in China and Monaco at the start of the current campaign before seeing his championship hopes fade in the races leading into August, said he started to realise this year that he might need a new challenge.

"In my mind I felt it was the right time to make a change," he said. "This year, particularly the first part of the year, I guess up until Monaco, was an amazing start for me, so many positives. There was a lot of good momentum and energy. But at times, for whatever reason, I felt personally a little frustrated, within myself and not necessarily with things happening at the team. I was just trying to understand why. When I weighed it up I thought a change of settings, new challenge, is probably the answer I need."

He went on to state that the decision was not down to dissatisfaction with the team itself or how he saw himself within it.

"I don't feel like my presence in the team this year has changed. I think it's probably shown, particularly on Sundays, the desire is still 100 percent there. The desire to race and be the best hasn't changed.... [missing some] Just laying in bed at night more things were running through my head, I was probably asking myself more questions about what I wanted, where I see myself."

He added: "I never said I was unloved [at Red Bull], that wasn't the case. I think there was no real highlight other than the routine. We don't have to a 9-5 job and we're not going to the same office every day but so many years of going to the same factory or whatever, that routine, I felt my enjoyment of the sport was becoming a little bit, I don't know, dulled down, a bit numb at times. I felt the routine was causing that a bit.

"I'm still discovering myself in life and it's changing pretty rapidly and maybe how I felt 12 months ago isn't how I feel now. The routine is something I felt was, I don't want to say getting the best of me, but it was clearly affecting me."

Timeline of decision and call to Helmut Marko

Red Bull was caught unawares by Ricciardo's decision, having gone into the summer break assuming an extension was simply a formality at that point. Helmut Marko, the head of the team's driver programme, said this week that the Australian driver had led him and other senior management figures to believe he would sign a deal, before calling back several days later to reveal his switch to Renault.

Ricciardo admitted it was a difficult call to make.

When asked about Marko's comments, he laughed and said: "It wasn't like that.

"It was tough, I don't like letting anyone down. Not many people get satisfaction out of letting others down. It was OK, a call I had to make. One which for sure made me a little nervous, but I think it went OK. Understanding in many ways. He's known me for 10 years and I think he'd sensed at times some frustration or maybe some things changing in me, so I don't think it completely surprised him but he was a little bit disappointed I was moving on.

"From my point of view it makes me sad to move on but it makes me proud to know I was wanted. It was all very calm and respectful, so, it was all I could ask for."

He said the decision had been a long time coming, rather than one made in the spur of the moment.

"To be clear, there was no falling out or any bad blood with anyone in the team, nothing at all. With the contract stuff people assumed I was pretty much done with Red Bull and ready to sign, but I'm pretty sure I always just said I was close to doing something. I never said it was 100 percent going to be with Red Bull. There wasn't anything that happened overnight which caused this decision."

"There was back and forth over the last few months. In the end, the deal, we'd come to a happy place with it. So then it was up to me, I guess I knew what was in front of me."

He added: "It is not something I knew for weeks or months. So, it was all pretty much when it got announced right before the break.

"Renault was part of my considerations for a bit of time, they didn't come out of nowhere in the last hour.

"I was really torn with what to do and that process took time. Still in the race weekend in Budapest I wasn't sure what I was going to be doing.

"I did the test on Tuesday, and had some time to think about it over those 48 hours and came to my decision.

"It wasn't easy. There were a lot of factors and variables I had to weigh up in my mind."

The Verstappen question

Ricciardo also refuted the suggestion his move was down to a fear of staying alongside current teammate Max Verstappen, something suggested by Red Bull boss Christian Horner after the news became official.

Asked if he felt increasingly uneasy to stay a team seemingly being built around Verstappen, he replied: "No is the short answer.

"I think externally, around the media and some fans perspectives as well that might be seen as the case, but honestly internally... Baku and that we had an incident and a couple of on-track things around ourselves but as far as [inequality] went within the team probably from the outside people thought that but hand on heart there was never any sign of that."