I have 2 WANs. One WAN with distance 1 and other with distance 2. Now the active WAN can be pinged from the internet. However the other WAN with a longer distance is never be able to pinged from the internet. I have a default rule in the firewall that allows ICMP ping to all interfaces. I know this is something pretty basic that I am missing here. Any help?

It's routing: without any special setup, ICMP ECHO replies will use default routing path regardless of original target IP address ... and if both WANs are active, this means the wrong WAN. Either the primary ISP will drop packet due to invalid source address or pinging workstation will ignore reply because it's coming from different remote address.

Just search this forum, it's full of examples how to do it properly.

Thanks. Will check this and get back to you if I fail to find something that I can use:)