If your young and healthy ... I think Viagra is not advisable. If you do need it, I think you may need medical assistance and there may be issues.
Older guys, it can help. But looking after your overall health is the best first step.
It does make a difference but I've found I have slight after effects that I don't like.
I don't take it anymore.
I focus on fitness and health.
But ... it does work if you need it.
Just take smallest dose that works and enjoy