Nico Hulkenberg conceded to suffering personal "degradation" on his return to F1.
Hulkenberg, who has replaced fellow German Mick Schumacher at Haas, completed 110 laps in the end-of-season test in Abu Dhabi.
Although Hulkenberg has spent the last two years as reserve and development driver with Aston Martin, he has only competed in four grands prix in the past three seasons overall after exiting the sport as a full-time driver in 2019.
Appreciably, Hulkenberg was feeling the effects of a full day in the cockpit of the VF-22.
"A good day of work, a good day of running, collected many impressions, a lot of data, which was the target," said Hulkenberg. "We successfully went through that programme.
"So a lot of things to pick through, to analyse and digest now in the next couple of weeks, but I'm satisfied and happy. There was nothing really unexpected or out of the blue, no surprises."
Hulkenberg given reminder of physical F1
Asked how he felt physically, particularly whether the day had taken a toll on his neck, he replied: "It's not just the neck, it's the body, too. The glutes have to work.
"It was hard, it was tough, I was feeling some degradation towards the end of the day but that was to be expected.
"Actually, I felt better than I expected, so that's good but obviously, [I've] three months of hard-core preparation now."
Hulkenberg claims a day such as in Abu Dhabi serves as a welcome reminder as to what he now has to do to get up to speed ahead of his return for the first race of next season in Bahrain in early March.
"It does show you again the intensity these cars have," added Hulkenberg.
"Then you add the race and the competition and it's another story again. I have a plan and I know what I'm going to have to do."