“Erection problem?”

It's important to understand that what is good for the heart is good for the penis. Exercising is good for the heart so it should if anything help improves blood flow to the penis. I think your less rigid erections may be coincidental to the timing of you starting to exercise and not caused by your exercise. If you smoke, drink excessively, use illicit drugs, have diabetes or high blood pressure- these are notorious causes of diminished erections or erectile dysfunction. Also, there is something called psychogenic erectile dysfunction- in which there may be a psychological cause. In this case, erections are weak due to performance anxiety, depression, guilt/shame, or relationship issues. In these cases, patients typically have normal morning wood or nocturnal erections and may have normal erections with self-stimulation but have trouble with erections during partnered sex. Take a note of how your erection quality is when you're alone, during partnered sex, and if you have normal morning wood/nocturnal erections. If you are still concerned, you should talk to a urologist like me formally.