Empowered by sophisticated Western-supplied weapons, the Ukrainian army has made significant advances in the east and the south, reclaiming towns and villages even in areas the Kremlin claims are now part of Russia.
President Zelensky said Russian forces were putting up a "good enough fight", but that Ukraine had received weapons - "I won't say we have enough now" - and soldiers were motivated to push forward.
The Russian military's setbacks, a major embarrassment for President Putin, have sparked unusual criticism of the country's military.
Amid the losses, President Putin announced the mobilisation of hundreds of thousands of reservists, which led to rare anti-war protests in Russia and to a huge exodus of military-age men.
President Zelensky urged Russians to "fight for your body, rights and soul", saying: "Those mobilised kids now, they come with nothing. Without guns or armour. They are being thrown here like cannon fodder... If they want to be kebabs - fine, let them come. But if they are people after all and think that this is their lives, they have to fight.
"Everything Putin is afraid of, and it's not the nuclear hit, he is afraid of his community," he said. He's afraid of his people. Because only those people are capable of replacing him nowadays. Take away his power. Give it to someone else."
Asked whether President Putin could survive in an eventual Ukrainian win in the war, he said: "I don't care."
