diff --git a/src/gui/activityWidget.cpp b/src/gui/activityWidget.cpp
index f14e0ad..eb9bb84 100644
--- a/src/gui/activityWidget.cpp
+++ b/src/gui/activityWidget.cpp
@@ -18,6 +18,7 @@ ActivityWidget::ActivityWidget(QWidget* parent) : QWidget(parent), mUi(std::make
     mUi->cbTimeSheetParams->setItemDelegate(new TimeSheetParamsItemDelegate);
 
     connect(mUi->btStartStop, &QPushButton::clicked, this, &ActivityWidget::onBtStartStopClicked);
+    connect(mUi->cbTimeSheetParams, &QComboBox::currentIndexChanged, this, &ActivityWidget::onTimeSheetParamsIndexChanged);
     connect(&mSecondTimer, &QTimer::timeout, this, &ActivityWidget::onSecondTimeout);
 
     mSecondTimer.setInterval(std::chrono::seconds(1));
@@ -110,6 +111,7 @@ void ActivityWidget::onSessionCacheSynchronizeFinished()
     }
 
     mTimeSheetParamsModel.updateDataFromCache(mSession->cache());
+    mUi->cbTimeSheetParams->setCurrentIndex(-1);
 }
 
 void ActivityWidget::onHistoryTimeSheetStartRequested(const TimeSheet& timeSheet)
@@ -136,7 +138,11 @@ void ActivityWidget::onHistoryTimeSheetFillRequested(const TimeSheet& timeSheet)
     fillFromTimesheet(timeSheet);
 }
 
-void ActivityWidget::fillFromTimesheet(const TimeSheet& timeSheet) {}
+void ActivityWidget::fillFromTimesheet(const TimeSheet& timeSheet)
+{
+    auto index = mTimeSheetParamsModel.findIndex(timeSheet.project.id, timeSheet.activity.id);
+    mUi->cbTimeSheetParams->setCurrentIndex(index);
+}
 
 void ActivityWidget::onBtStartStopClicked()
 {
@@ -144,9 +150,10 @@ void ActivityWidget::onBtStartStopClicked()
     {
         stopCurrentTimeSheet();
     }
-    else
+    else if (isCurrentTimeSheetParamsValid())
     {
         TimeSheet timeSheet;
+        std::tie(timeSheet.project.id, timeSheet.activity.id) = getCurrentTimeSheetParams();
 
         auto timeSheetResult = mSession->client()->startTimeSheet(timeSheet, mSession->timeSheetConfig().trackingMode);
 
@@ -158,6 +165,11 @@ void ActivityWidget::onBtStartStopClicked()
     }
 }
 
+void ActivityWidget::onTimeSheetParamsIndexChanged(int /*index*/)
+{
+    mUi->btStartStop->setEnabled(isCurrentTimeSheetParamsValid());
+}
+
 void ActivityWidget::updateControls()
 {
     // Can be raised while clearing combobox on session changes
@@ -219,3 +231,15 @@ void ActivityWidget::startPendingTimeSheet()
         connect(timeSheetResult, &KimaiApiBaseResult::error, [timeSheetResult]() { timeSheetResult->deleteLater(); });
     }
 }
+
+bool ActivityWidget::isCurrentTimeSheetParamsValid() const
+{
+    return mUi->cbTimeSheetParams->currentData(TimeSheetParamsModel::ProjectIdRole).isValid() &&
+           mUi->cbTimeSheetParams->currentData(TimeSheetParamsModel::ActivityIdRole).isValid();
+}
+
+std::pair<int, int> ActivityWidget::getCurrentTimeSheetParams() const
+{
+    return {mUi->cbTimeSheetParams->currentData(TimeSheetParamsModel::ProjectIdRole).toInt(),
+            mUi->cbTimeSheetParams->currentData(TimeSheetParamsModel::ActivityIdRole).toInt()};
+}
diff --git a/src/gui/activityWidget.h b/src/gui/activityWidget.h
index ba662c6..bb24b13 100644
--- a/src/gui/activityWidget.h
+++ b/src/gui/activityWidget.h
@@ -26,6 +26,7 @@ class ActivityWidget : public QWidget
 
 private:
     void onBtStartStopClicked();
+    void onTimeSheetParamsIndexChanged(int index);
 
     void onSecondTimeout();
 
@@ -42,6 +43,9 @@ class ActivityWidget : public QWidget
 
     void startPendingTimeSheet();
 
+    bool isCurrentTimeSheetParamsValid() const;
+    std::pair<int, int> getCurrentTimeSheetParams() const;
+
     std::unique_ptr<Ui::ActivityWidget> mUi;
     QTimer mSecondTimer;
     std::shared_ptr<KemaiSession> mSession;
diff --git a/src/gui/timeSheetParamsItemDelegate.cpp b/src/gui/timeSheetParamsItemDelegate.cpp
index 602604e..09b36a8 100644
--- a/src/gui/timeSheetParamsItemDelegate.cpp
+++ b/src/gui/timeSheetParamsItemDelegate.cpp
@@ -47,11 +47,6 @@ void TimeSheetParamsItemDelegate::paint(QPainter* painter, const QStyleOptionVie
     // Activity
     auto activityRect = QRect(textX + widthThird, secondLineY, 2 * widthThird, textH);
     qApp->style()->drawItemText(painter, activityRect, Qt::AlignLeft, option.palette, isSelected, index.data(TimeSheetParamsModel::ActivityName).toString());
-
-    if (option.showDecorationSelected)
-    {
-        qDebug() << index.data().toString();
-    }
 }
 
 QSize TimeSheetParamsItemDelegate::sizeHint(const QStyleOptionViewItem& option, const QModelIndex& index) const
diff --git a/src/models/timeSheetParamsModel.cpp b/src/models/timeSheetParamsModel.cpp
index b8b151a..b9306b6 100644
--- a/src/models/timeSheetParamsModel.cpp
+++ b/src/models/timeSheetParamsModel.cpp
@@ -12,7 +12,7 @@ void TimeSheetParamsModel::updateDataFromCache(const KimaiCache& cache)
         {
             for (const auto& activity : cache.activities(project.id))
             {
-                m_timeSheetParams.emplace_back(TimeSheetParams{
+                mTimeSheetParams.emplace_back(TimeSheetParams{
                     .customer = customer.name, .project = project.name, .activity = activity.name, .projectId = project.id, .activityId = activity.id});
             }
         }
@@ -21,15 +21,26 @@ void TimeSheetParamsModel::updateDataFromCache(const KimaiCache& cache)
     endResetModel();
 }
 
-QVariant TimeSheetParamsModel::data(const QModelIndex& index, int role) const
+int TimeSheetParamsModel::findIndex(int projectId, int activityId) const
 {
+    auto it = std::find_if(mTimeSheetParams.begin(), mTimeSheetParams.end(), [projectId, activityId](const auto& timeSheetParams) {
+        return timeSheetParams.projectId == projectId && timeSheetParams.activityId == activityId;
+    });
+    if (it == mTimeSheetParams.end())
+    {
+        return -1;
+    }
+    return std::distance(mTimeSheetParams.begin(), it);
+}
 
-    if (!index.isValid() || (index.row() > m_timeSheetParams.size()))
+QVariant TimeSheetParamsModel::data(const QModelIndex& index, int role) const
+{
+    if (!index.isValid() || (index.row() > mTimeSheetParams.size()))
     {
         return {};
     }
 
-    const auto& params = m_timeSheetParams.at(index.row());
+    const auto& params = mTimeSheetParams.at(index.row());
     switch (role)
     {
     case Qt::DisplayRole:
@@ -57,5 +68,5 @@ QVariant TimeSheetParamsModel::data(const QModelIndex& index, int role) const
 
 int TimeSheetParamsModel::rowCount(const QModelIndex& /*parent*/) const
 {
-    return static_cast<int>(m_timeSheetParams.size());
+    return static_cast<int>(mTimeSheetParams.size());
 }
diff --git a/src/models/timeSheetParamsModel.h b/src/models/timeSheetParamsModel.h
index 47525db..a671f9c 100644
--- a/src/models/timeSheetParamsModel.h
+++ b/src/models/timeSheetParamsModel.h
@@ -20,6 +20,9 @@ class TimeSheetParamsModel : public QAbstractListModel
 
     void updateDataFromCache(const KimaiCache& cache);
 
+    // Returns -1 if not found
+    int findIndex(int projectId, int activityId) const;
+
     QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override;
     int rowCount(const QModelIndex& parent = QModelIndex()) const override;
 
@@ -32,7 +35,7 @@ class TimeSheetParamsModel : public QAbstractListModel
         int projectId;
         int activityId;
     };
-    std::vector<TimeSheetParams> m_timeSheetParams;
+    std::vector<TimeSheetParams> mTimeSheetParams;
 };
 
 } // namespace kemai