Feeling helpless...

I have no idea what to do with my 4 month old son. I mean, you can only jump in a jumperoo, do tummy time, swing, and bounce in your bouncer for so long. I feel like he is getting bored. They can do that you know. Get bored. I also feel guilty when I'm not right there with him 24/7 while he is awake. Is that wrong? I mean, I feel like I get absolutely nothing done. Our favorite thing to do here lately is to go for a walk. But, it has been so cold the past few days, that has been out of the question. I guess the reason for this blog is that I feel helpless. I don't want him just lying around on his back. I feel like he needs to be active, but I have no idea what to do. If there are any ideas out there, or you have been through this too, please tell me and let me know what you did! :)