Restarting exercise after an extended break can be challenging.
I believe it is more challenging for many people than starting in the first place.
When we first start exercising - for whatever reason - things can only get better. In some sense, it's all progress. We're learning and improving in our health; we're feeling, functioning and looking better with our progressive exercise efforts.
And then, just like that, it stops. Maybe the reason for the stoppage is tragic or insurmountable; maybe it's just poor planning (it's usually a combination of the two).
Restarting exercise forces us to face what we've lost in feel, function and look since the latest stoppage. Comparison is the thief of proper perspective in this instance. And, that can be painful, especially if you were more culpable than you were victimized in your stoppage.
For me, the key to getting both passed this and over myself is to see exercise as an ongoing process. All that ever matters is here and now. Onward.