I'm 46 and had a heart attack what exercise are safe?

Walking: Start off walking either outside if weather is mild, or on a treadmill or indoor facility. Later you can try weight or exercise machines as long as your doctor gives you permission and you don't have symptoms.

Very hard to say: Very hard to say. Depends on the details of what type of heart attack, how it was treated, and whether you have continued symptoms. You should really meet with your cardiologist to discuss this.