Cape Town - Toro Rosso's Brendon Hartley concedes he wasn't ready to compete at the highest level when he was initially given a shot by Red Bull, but feels he is a "more rounded" driver now.
The New Zealander had his first taste of Formula 1 action as an 18-year-old in 2008 when tested for Red Bull and the following year he was named the official reserve driver for the Milton Keynes team as well as Toro Rosso.
However, he was dropped from the Red Bull Junior Team in mid-2010, but instead of drowning in self-pity, he got his act together and competed in other series.
He was given another chance in Formula 1 this year when Toro Rosso asked him to stand in for Pierre Gasly at the US Grand Prix and he was eventually given Daniil Kvyat's full-time seat.
Hartley admits he didn't have enough experience when he made his initial breakthrough.
"I wasn't ready at that point," he told Motorsport.tv programme The Flying Lap.
"I have big respect for the likes of Max [Verstappen], who has come in at the age that I was.
"I had a real opportunity to be there, but when it came down to it I didn't have all the experience that I needed and maybe support and I crumbled when I shouldn't have."
The 28-year-old believes he learned a lot of lessons during his first stint and feels he has upped his game since then.
"I learned a lot from that and I feel like I'm a lot more rounded driver today than I ever could have been at 18," he added.
"The timing has been perfect and I think you keep on improving.
"I had a tough time, but it was also important for me to learn from."