diff --git a/fitbitsync.py b/fitbitsync.py
index 100fb97..56bd872 100644
--- a/fitbitsync.py
+++ b/fitbitsync.py
@@ -22,10 +22,16 @@ except ImportError:
     FITBIT_LIBRARY = False
 
 try:
-    import garminconnect
-    GARMIN_LIBRARY = "garminconnect"
+    import garth
+    GARTH_LIBRARY = True
 except ImportError:
-    GARMIN_LIBRARY = None
+    GARTH_LIBRARY = False
+
+try:
+    import garminconnect
+    GARMINCONNECT_LIBRARY = True
+except ImportError:
+    GARMINCONNECT_LIBRARY = False
 
 import schedule
 
@@ -555,34 +561,12 @@ class GarminClient:
             self.garminconnect = garminconnect
             logger.info("Using garminconnect library")
             
-            # Monkey patch the login method to handle garth compatibility issue
-            original_login = self.garminconnect.Garmin.login
-            
-            def patched_login(self):
-                """Patched login method that handles garth returning None"""
-                try:
-                    result = original_login(self)
-                    return result
-                except TypeError as e:
-                    if "cannot unpack non-iterable NoneType object" in str(e):
-                        # Check if we have valid tokens despite the None return
-                        if (self.garth.oauth1_token and self.garth.oauth2_token):
-                            logger.info("Login successful (handled garth None return)")
-                            return True
-                        else:
-                            raise
-                    else:
-                        raise
-            
-            # Apply the patch
-            self.garminconnect.Garmin.login = patched_login
-            
         except ImportError:
             logger.error("garminconnect library not installed. Install with: pip install garminconnect")
             raise ImportError("garminconnect library is required but not installed")
     
     async def authenticate(self) -> bool:
-        """Authenticate with Garmin Connect"""
+        """Authenticate with Garmin Connect using garth"""
         if self.read_only_mode:
             logger.info("Running in read-only mode - skipping Garmin authentication")
             return True
@@ -597,54 +581,24 @@ class GarminClient:
                 if not self._setup_credentials():
                     return False
 
-            logger.info("Initializing Garmin client...")
+            # Set session file path for garminconnect library
+            os.environ['GARMINTOKENS'] = str(self.session_file)
+
+            # Configure garth for domain if using Garmin China
+            if self.is_china:
+                garth.configure(domain="garmin.cn")
+
+            # Initialize garminconnect.Garmin with credentials.
+            # It will use garth library for authentication and session management.
             self.garmin_client = self.garminconnect.Garmin(
-                self.username,
-                self.password,
-                is_cn=self.is_china
+                self.username, self.password
             )
+            self.garmin_client.login()
 
-            # Use garth to load the session if it exists
-            if os.path.exists(self.session_file):
-                try:
-                    logger.info(f"Attempting to load session from {self.session_file}")
-                    self.garmin_client.garth.load(self.session_file)
-                    logger.info("Loaded existing session from file.")
-                    # Log garth state after loading
-                    logger.info(f"Garth tokens after load: oauth1={bool(self.garmin_client.garth.oauth1_token)}, oauth2={bool(self.garmin_client.garth.oauth2_token)}")
-                except Exception as e:
-                    logger.warning(f"Could not load session file: {e}. Performing fresh login.")
-
-            # Login (will use loaded session or perform a fresh auth)
-            logger.info("Calling garmin_client.login()...")
-            try:
-                # Handle garth API compatibility issue - newer versions return None
-                # when using existing sessions, but garminconnect expects a tuple
-                login_result = self.garmin_client.login()
-                
-                # Check if login returned None (new garth behavior with existing sessions)
-                if login_result is None:
-                    # Verify that we actually have valid tokens after login
-                    if (self.garmin_client.garth.oauth1_token and
-                        self.garmin_client.garth.oauth2_token):
-                        logger.info("Login successful (garth returned None but tokens are valid)")
-                    else:
-                        logger.error("Login failed - garth returned None and no valid tokens")
-                        raise Exception("Garmin login failed: No valid tokens after authentication")
-                else:
-                    logger.info("Login successful")
-                    
-            except Exception as e:
-                logger.error(f"Login failed with exception: {e}")
-                # Log garth state before re-raising
-                logger.info(f"Garth tokens before failure: oauth1={bool(self.garmin_client.garth.oauth1_token)}, oauth2={bool(self.garmin_client.garth.oauth2_token)}")
-                raise
-
-            # Save the session using garth's dump method
-            self.garmin_client.garth.dump(self.session_file)
-
+            # Verify by getting the full name
             profile = self.garmin_client.get_full_name()
-            logger.info(f"Successfully authenticated and saved session for user: {profile}")
+            logger.info(f"Successfully authenticated with Garmin for user: {profile}")
+
             return True
 
         except Exception as e:
@@ -653,6 +607,10 @@ class GarminClient:
             logger.error(f"Full traceback: {traceback.format_exc()}")
             return False
 
+    def _mfa_handler(self, _) -> str:
+        """Handle MFA code input from the user."""
+        return input("Enter Garmin MFA code: ")
+
     def _setup_credentials(self) -> bool:
         """Setup Garmin credentials interactively"""
         print("\n🔑 Garmin Connect Credentials Setup")