Watch only works when not worn

This watch will keep great time if it has been wound via crown.

When a watch is on a desk, the balance wheel is vertical, when you are wearing it the balance wheel horizontal.

Has the watch been dropped onto a hard surface?

If the balance wheel bearing is worn or has suffered a large shock, then the shaft may move in its bearings or the bearings damaged, which may give the problem you decscribe.

Take it to a watch repairer to have it adjusted or repaired.

normally automatic watch need to wear at least 8hrs in a day ,then it works for next 30hrs.if it stops or loosing time, it indicates that needs service with lubrication .

These watches are self winding (mechanical spring), so need to be worn (or gently oscillated) to wind them up.

The catalogue for this watch says it should run for 72 hours when fully wound.

Depending on when the watch was made, it could be that it needs a clean.

Try wearing it for a few days to see if it keeps going.

This usually happens when the watch is carried from low temperature to the room with higher temperature and it's called condensation. You need to dry out your watch and check if all the gaskets are in tact, flexible and lubricated. Don't leave it for a long, as later those tiny drops of condensate will sit down on gear wheels, causing them to rust and as a consequence will stop the watch working. Any watch repair shop will be able to help within a matter of an hour.
Rate me, plz.

There is nothing wrong with your watch. Probably it's the one measuring heart rate and pulse (heart beats per second).
Use your users manual to set the watch.
By the way: Timex is one of the worst watch producers.

The Tag Heur repair center says an automatic watch must go through an "initiation" process. They recommend winding manually 40 revolution of the crown clockwise. You must wear an automatic watch at least eight hours per day. Repat the initiation if the watch is not worn for 20 hours or so.

Your watch is an automatic watch which means it winds itself as long as you are wearing it. If you don't wear it for several days it will stop working. To solve this situation buy an automatic watch winder to keep your watch in while you are not wearing it and it will keep the correct time.

Since it's eco-drive you can just wear it for a few hours and it should self-wind. The problem is that when it sits still for more than a few days it winds down. It gets its power from the natural movement of your wrist as you walk around.

Once it starts ticking again you'll just have to set the time correctly.

The Tag Heur repair center says an automatic watch must go through an "initiation" process. They recommend winding manually 40 revolution of the crown clockwise. You must wear an automatic watch at least eight hours per day. Repat the initiation if the watch is not worn for 20 hours or so.