How do you build endurance? Run at the same pace for as long as you can without stopping. Run the same distance or longer next time. Run the same speed or faster. Increase gradually. Sure, any exercise helps to some extent, but this is the most efficient.

Get your breathing in a routine. Try to breath deep and exhale slow.

Don’t quit smoking. Smoking makes you look cool. You’re being healthy and running already so there’s no reason to get all extreme about it. Also when you can outrun somebody who doesn’t smoke you can be like “Yeah, I outrun you and smoke LOL” so it makes you even more badbum than if you didn’t smoke.