Use 'embark upon' when starting something new and challenging with a sense of adventure.

Fresh Endeavors

It implies a serious commitment to a new task, often with a considerable investment of time or effort.

Serious Undertaking

'Embark upon' is often used metaphorically to suggest the beginning of a journey or quest.

'Embark upon' in travel means to start a trip, usually by boarding a vehicle.

The phrase suggests the action of boarding is about to happen or has just started.

More formal than 'get on', often used in official announcements or written instructions.