People warned him he'd get bored - he didn't - but he did recognise that he likes doing things that make money.
"Personally I'm quite coin operated so it's not particularly satisfying just watching a balance in a stock account go up or go down." Valentine could have jumped back into another start-up, but says he doesn't have the desire, enthusiasm or energy to start from scratch again.
"I think part of being a successful start-up involves having a bloody lot of tenacity and I probably haven't got a lot of that left."
Taking the time to figure out what interested him, particularly over the long term, resulted in trying angel investing, only to find that didn't satisfy his desire to add value as well as funding.
"Also, maybe I'm a little bit too selfish in that I don't want to do a whole bunch of work for other people when I've only got $20,000 in."
He's found a good investment match with a company called PitchMetrics, a cloud-based sales and marketing tool looking to push its product into the North American market.
Valentine knows the US business environment well, having successfully taken Zeacom there in the late 1990s.
He says that while there's now more support, education and mentoring available for high growth businesses looking to crack international markets, nothing beats the expertise of someone who has done it all before.
It's one of the reasons he looks for "coachability" in the executives of any business in which he takes a stake.
"If I detect the CEO is not coachable I'm not interested.
"At all."
Valentine says New Zealand companies aiming for overseas markets need to think big right from the start.
"And we don't. We were guilty of this at Zeacom, absolutely.
"It took us a long time to figure out how wrong we were."
He says New Zealand companies heading to North America need to lift their eyes above the small-to-medium business market and aim for corporates.
"Sell the sales that are worth hundreds and hundreds of thousands of dollars as opposed to 30 to 40 [thousand] because that's what makes it worthwhile.
"That's what makes you more successful but because we do come from small-to-medium, we feel very good at that space and we feel an affinity for it and so inevitably we find ourselves doing it.
"You've got to sell an awful lot of things at 20 to 30 grand to make a meaningful number, as opposed to selling something for $200,000 or $300,000 or $400,000."
In the case of PitchMetrics, he says, a good-sized sale in New Zealand would be to a company with a sales force of 300 people.
In the United States he wants it to push a market where it's selling to companies with no less than 1000 people in a sales team. To do that, PitchMetrics needs to be structuring its product now to match the scale and demands of those clients, he says.
Valentine doesn't just have an affinity with PitchMetrics' goals to conquer the US; he also loves the product.
Since his first business selling telephones in the late 1980s, Valentine has been very sales-driven and he could see the potential to add substantial value beyond his investment stake, incorporating his sales experience into the product design.
He's also taking his passion for selling to help salespeople hone their skills with a training business, Sales Builder.
Valentine says most people get into sales because they have the "gift of the gab" but very few have any understanding of the different sales theories, models and process.
"Frankly I've always loved that." The importance of having a well-trained sales force came from his telephone selling days, when the company adopted methods espoused by training guru Brian Tracy and destroyed the competition, growing sales from nothing to $12 million in four years before selling the business to U-Bix.
He says sales is a dirty word in business, thanks to the "horrible old sales methods" used by the likes of the Encyclopaedia Britannica salesmen.
"For me, for my career, it's always been about sales and therefore this thing that I'm doing now, this sales training, it's almost the conclusion of all the things that I've done previously.
"It's always been about sales.
"Every single business that you think of right now, it's all about revenue and we as the managers often don't give it enough focus."