Thread Problems in Java FX

Good evening,

I'm having problems trying to implement a thread to my application, I always get the same error and I do not know how to solve it.

When I run the application the first Thread goes into effect, but when it executes the second it generates the error.

Here is a sample class:

package ajuda;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.concurrent.Service;
import javafx.concurrent.Task;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;

public class AjudaController implements Initializable {

    @FXML
    private Label texto;

    private void Thread1() {

        Service service = new Service() {
            @Override
            protected Task createTask() {
                return new Task() {
                    @Override
                    protected Object call() throws Exception {

                        texto.setText("Alguma coisa");
                        Thread2();
                        return null;
                    }
                };
            }
        };
        service.start();
    }

    private void Thread2() {

        Service service = new Service() {
            @Override
            protected Task createTask() {
                return new Task() {
                    @Override
                    protected Object call() throws Exception {

                        texto.setText("Alguma coisa 2");
                        return null;
                    }
                };
            }
        };
        service.start();
    }

    @Override
    public void initialize(URL url, ResourceBundle rb) {
        Thread1();
    }
}

Every time I run I get the same error:

mai 24, 2018 12:14:53 AM javafx.concurrent.Service lambda$static$488
WARNING: Uncaught throwable in javafx concurrent thread pool
java.lang.IllegalStateException: Not on FX application thread; currentThread = Thread-5
    at com.sun.javafx.tk.Toolkit.checkFxUserThread(Toolkit.java:279)
    at com.sun.javafx.tk.quantum.QuantumToolkit.checkFxUserThread(QuantumToolkit.java:423)
    at javafx.scene.Parent$2.onProposedChange(Parent.java:367)
    at com.sun.javafx.collections.VetoableListDecorator.setAll(VetoableListDecorator.java:113)
    at com.sun.javafx.collections.VetoableListDecorator.setAll(VetoableListDecorator.java:108)
    at com.sun.javafx.scene.control.skin.LabeledSkinBase.updateChildren(LabeledSkinBase.java:575)
    at com.sun.javafx.scene.control.skin.LabeledSkinBase.handleControlPropertyChanged(LabeledSkinBase.java:204)
    at com.sun.javafx.scene.control.skin.LabelSkin.handleControlPropertyChanged(LabelSkin.java:49)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase.lambda$registerChangeListener$61(BehaviorSkinBase.java:197)
    at com.sun.javafx.scene.control.MultiplePropertyChangeListenerHandler$1.changed(MultiplePropertyChangeListenerHandler.java:55)
    at javafx.beans.value.WeakChangeListener.changed(WeakChangeListener.java:89)
    at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:182)
    at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
    at javafx.beans.property.StringPropertyBase.fireValueChangedEvent(StringPropertyBase.java:103)
    at javafx.beans.property.StringPropertyBase.markInvalid(StringPropertyBase.java:110)
    at javafx.beans.property.StringPropertyBase.set(StringPropertyBase.java:144)
    at javafx.beans.property.StringPropertyBase.set(StringPropertyBase.java:49)
    at javafx.beans.property.StringProperty.setValue(StringProperty.java:65)
    at javafx.scene.control.Labeled.setText(Labeled.java:145)
    at ajuda.AjudaController$2$1.call(AjudaController.java:50)
    at javafx.concurrent.Task$TaskCallable.call(Task.java:1423)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at javafx.concurrent.Service.lambda$null$493(Service.java:725)
    at java.security.AccessController.doPrivileged(Native Method)
    at javafx.concurrent.Service.lambda$executeTask$494(Service.java:724)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)