How can I do this or how can I do it better?

[Uglyoldpoorman]

I have seen a drill where a target comes towards you and you have to shoot it as it advances.

My simple idea is to build a (u) shaped 15 foot track using 2x4"s and a little red wagon. First buy the little red wagon and fit the track to it. Then fit a target on the wagon..NOTE...wind/drag will be a factor but a few sand bags plus or minus should fix it.
Then using a rope pull it towards the shooter.

Thoughts please

[owlhoot]

Quite frankly this is a very easy scenario, one that you will not hold your interest for long. However, If you insist on doing it, sink two 8' poles in the ground then run a light cable between the two poles, fasten one end higher than the other and fix it so you can vary the height and thereby vary the speed. You can make this arrangement as simple or as complex as you wish. Locate it in a place where you can also use it as a horizontal running man target. There are many ways to attach wheels, pulleys, etc.

[The Lone Haranguer]

For a little extra challenge, you can put a curvature and/or stepped elevation in your tracks so as to make the target bob and weave as it comes toward you.