It did not do Lennox Lewis any harm... The secret is to do what Joshua is seemingly doing and Lewis and indeed Tyson did: Fight often, that way you get up to 15/20-0 inside a couple of years, and hopefully a year or so down the line some journeyman is good enough to take him six/eight rounds (ala Ocasio and Ferguson), then he will be ready to step up and dominate the domestic and European scenes for 12 months or so before challenging himself at world level.