Sir Keir Starmer has said he "hated selling myself" to party members during his recent campaign to become Labour leader.
He told the BBC's Coronavirus Newscast he found the experience of going up against party colleagues "very odd".
He added it was "the same in all political parties," but he was "much more comfortable" in a decision-taking role.
Sir Keir succeeded Jeremy Corbyn after a 12-week contest ending this month.
The 57-year-old former lawyer defeated Lisa Nandy and Rebecca Long-Bailey on the first round of voting, with more than 50% of ballots cast.
Sir Keir has given both his former rivals posts in his shadow cabinet team, in keeping with a commitment he made during the campaign.
He told the BBC: "You're in your own party and you're up against colleagues, and very good colleagues, who you like. And it is a very odd thing to do.
"I'm very glad that that part of it is over I have to say.
"For me personally, I really hated selling myself to the membership and I much prefer leadership decisions as leader.
"I'm much more comfortable in this than I am in the campaign."
He added that the coronavirus crisis now "frames everything" in terms of how the Labour party will conduct itself as an opposition party.
He said he wanted to be "constructive" throughout the crisis, adding the country would need a "different kind of opposition because of the circumstances we're in".
Labour has backed the government's decision to extend lockdown restrictions for "at least" another three weeks, but has called on ministers to publish their strategy for easing the measures.