Yes, exercise can have a big effect on fertility, both if you exercise too much or too little.
There is quite a lot of research on exercise and PCOS, because this is a condition marked by hormonal and blood sugar imbalance, which exercise is known to help with.
However, it is important to clarify the type of exercise and intensity level that you partake in.
For example, if your adrenal hormones are lower than average, then a high intensity spinning/kettle bell class might leave you feeling exhausted because you would be burning up too much Cortisol.
For most women that I would see I generally recommend very short bursts of intense exercise. e.g. 10-12 minutes maximum, allowing an extra few minutes for warm-up and stretching afterwards, three times per week, allowing gap days for recovery.
On recovery days, you could do some yoga/pilates/swimming/walking/rebounder but nothing too taxing, just enough to get the circulation moving.
7-10 minutes of weight training a couple of days a week with heavy enough weights that you find it hard to complete more than 12 repetitions is a great way to stabilise blood sugar levels and help hormonal balance. Women are commonly put off by the idea of weights, but it is something that is very easy to manage in the comfort of your own home with a good quality instructional video on youtube.
If you are nervous, then start out with a trainer in a gym until you feel comfortable to carry on with it yourself either at home or at a group class.
Exercise is great for ‘clearing’ the mind, which from my experience dealing with women and their fertility issues is a welcome benefit as internalised stress, grief, anger, frustration etc.. is never going to be helpful for a person’s health.
It’s also important to remember that whatever exercise you choose, it should be fun as otherwise you are unlikely to continue with it.