Zelenskyj only briefly commented on the course of the fighting in the east of the country, where Ukrainian troops had to give up the city of Lysychansk at the weekend.
The Russian armed forces have thus largely brought the Luhansk region under their control - which was considered one of their key war objectives.
The Ukrainian armed forces inflicted casualties on the Russian military every day, Zelenskyy said.
"We have to break them." That will take time and "superhuman effort", but there is no alternative to secure Ukraine's future.
Selenskyj was convinced that occupied areas would be recaptured.
Zelenskyy: Start reconstruction of Ukraine before end of war
Ukrainian President Volodymyr Zelenskyy has called for the country to start rebuilding quickly and not wait for the Russian war of aggression to end.
In the areas alone from which Russian troops have been driven out, there are tens of thousands of destroyed houses.
Rocket and grenade fire was reported from the north-eastern Sumy region, injuring several people.
Provide energy in winter
Zelenskyy said in his daily video speech that Ukraine must start preparing for the winter now, among other things to secure the energy supply.
Large parts of the economy have been paralyzed by fighting and Russian attacks.
Thousands of companies are at a standstill.
At the same time, reconstruction must be about more than just putting up walls that have been destroyed: "Ukraine must become the freest, most modern and safest country in Europe."
The first major conference on the reconstruction of Ukraine is currently taking place in Lugano, Switzerland.
The Ukrainian Prime Minister Denys Schmyhal estimated there on Monday that at least 750 billion dollars (almost 720 billion euros) would be necessary for this.
Ukrainian General Staff: Fighting now continues in Donetsk region
In eastern Ukraine, after the Ukrainian retreat from Lysychansk, the focus of fighting shifted to the neighboring Donetsk region.
On the border with the Luhansk region, Russian attacks were successfully repelled near Bilohorivka and Verkhnjokamyanske, the Ukrainian general staff said on Facebook on Monday evening.
The Wuhlehirsk thermal power plant to the west of Svitlodarsk, which has already been conquered by pro-Russian separatists, is also contested.
On the other hand, the Russian troops had gained territory north of Slowjansk near Masanivka.
In addition, Ukrainian positions on large parts of the front were shelled with artillery, rocket launchers and mortars.
The Russian air force also bombed positions of Ukrainian units.
Zelenskyy's adviser Oleksiy Arestovych expressed confidence that Ukrainian troops will be able to stabilize the defense lines on other front sectors after the abandonment of Lysychansk.
Overall, however, one can say that Russia's military has conquered the Luhansk region, he admitted on YouTube.
Administration in the Cherson region based on the Russian model
Meanwhile, Russia is stepping up efforts to cement its control over occupied Ukrainian territories.
In the southern region of Cherson, for example, after the introduction of the ruble as a currency and the issuing of Russian passports, administrative structures based on the Russian model are to be set up.
The goal is integration into the Russian Federation, stressed the deputy head of the Russian military administration, Kirill Stremousov, on the Telegram news service.
On Tuesday, a new regional government should start work.
Occupation Authorities: Ready for IAEA inspection at Zaporizhia NPP
The administration installed by Russia has shown itself open to the visit of representatives of the Atomic Energy Agency (IAEA) to the Zaporizhia nuclear power plant, which is located in the occupied territory.
"We are absolutely ready to let IAEA experts on the object," the chief of the occupation administration, Yevgeny Balitsky, told the Russian state news agency TASS.
A fire in a training building at Europe's largest nuclear power plant during a Russian attack in early March had sparked great international concern.
Balizki emphasized that the occupation authorities could not place the facility under their complete control according to IAEA specifications, but would have to operate it together with Ukraine.
Scholz advises Macron on further Ukraine course
Chancellor Olaf Scholz met with French President Emmanuel Macron in Paris for consultations.
The most important topic was the Franco-German vote on how to proceed in the Ukraine war and continued support for the country, as the Élysée Palace announced on Monday evening.
In this context, it was also about steps towards European independence in the areas of energy, defense and strategic raw materials.
Scholz and Macron visited the Ukrainian capital Kyiv together last month.
That will be important on Tuesday
The conference on the reconstruction of Ukraine ends in Lugano, Switzerland.
Zelenskyy promised "maximum transparency" on all projects amid concerns about corruption in his country.
The accession protocols required for the admission of Sweden and Finland are to be signed at NATO headquarters in Brussels in the morning.
The ceremony will be attended by representatives of all 30 member states.
Due to the subsequent ratification process in the allied states, it is estimated that it could take another six to eight months before Finland and Sweden can actually be accepted into the military alliance.